Much has been said over the years about the difficult mother-in-law - but what if the daughter-in-law (or son-in-law, for that matter) is the one who sets the tone of contention and friction? If your relationship with your daughter or son-in-law is difficult and you feel like you're trying to walk through a minefield every time you get together, you're going to need to tread carefully. Accepting the fact that s/he is the one your child chose to marry is important, and there are things you can do to "grease the wheels", paving the way to a smoother sail in this tricky relationship. Does your relative or in-law actually need psychological assistance; well you can help them get it. For ease of reading, assume the child-in-law is a difficult daughter-in-law.
Respect your child's choice. Your son/daughter loves this woman, no matter that you can't understand what he sees in her. Remember the old song, "When a man/woman loves a woman...If she is bad, he can't see it, She can do no wrong, Turn his back on his best friend if he put her down." This is absolute truth - so in dealing with her, no matter what your true feelings are, you must never say a word against her to your son.
Stay cordial at all times. She may be a clueless, crude boor. She may be vulgar and crass. She may swear like a sailor while your family is a church-going, proper group. She may actually be unkind, cruel, or a manipulative, controlling narcissist, not caring about imposing on others as long as she gets whatever she wants. There is nothing you can do about this. Just be polite, as you would be to a stranger. The only real exception to this is if you have little kids (your son has siblings who have children, perhaps) around and she's cursing like crazy - then you might say, mildly, "Ooh - can we watch the language while the kids are here? They get into trouble for saying that word and I don't want them to pick it up here. Thanks." No matter how creepy she is, stay calm, cool, poised, and polite.
Set your boundaries as you are comfortable. Perhaps you don't wish to support this union any more than is absolutely necessary to maintain some relationship with your son. That's your choice, absolutely. So simply set things up so that they are clear from the beginning. If your daughter-in-law makes snide or nasty remarks about another family member (perhaps your other daughter-in-law), say, "Well, she may not have much fashion sense, but she is one of the sweetest people I know, and I love her very much." This lets her know, in a calm, non-critical way, that you will not be interested in hearing her snipe at this person. If she drops over unannounced, don't lie but stop her at the door with a regretful but firm, "I'm sorry, Allison - and think of something that you need to do like I'm just about to go and run my errands, so I need to fly. And you know what - it really is best to give a call ahead, just so I'm not in the shower, or doing my nude dancing or whatever." Then grin and go back inside. If she tells you she'd like to tag along, let her know you're picking up a friend and this was time you had set aside to visit with that friend. Tell her you only get time with your friend so often, and you would not appreciate it if your friend brought someone else along at the last minute, and that you will respect that little propriety this time, "...but if you let me know ahead of time that you'll be coming by, I can either reschedule my running around with Bernice, or ask if she'd mind if you joined us - that'd be fine for next time!" Keep it positive.
Remember that she may be the mother of your grandchildren. She will control access to any offspring of your son's that result from the marriage. Your best bet to retain visitation is to maintain a cordial, amicable relationship - bite your tongue if you must to remain civil. Don't criticize her parenting, don't get angry if she changes plans at the last minute, leaving you out in the cold when you had planned to have the kids over for the weekend. This is one of the ways that certain people control situations and others (see How to Recognize a Manipulative or Controlling Relationship) - the best you can do is to understand that she has the ultimate say over what happens with her children. And don't kid yourself that you have a lot of rights: courts do not tend to side with grandparents unless the mother and/or father are declared unfit or have been arrested for a felony. Just try as best you can to keep your relationship workable, no matter how bloody your tongue gets.
Talk to your son or daughter. Careful, though. Don't just unload a litany of your daughter-in-law's hateful traits. Instead, try to take an approach that is diplomatic and not critical. State the problem, and then request your preferred solution:
Example 1: Your daughter-in-law was supposed to drop your grandkids off for a sleepover on Friday night, but didn't show. You wait an hour and a half before finally calling your son, worried and upset, to find that their plans changed and they have called off the visit. Wisely, you wait a day, then call your son or daughter again to discuss a more suitable way to handle such an issue.
You: "Josh, you asked us if we'd like to take the kids last weekend. Allison was supposed to drop them off around 5pm on Friday night and pick them up at noon on Sunday. Instead, Allison was a no-show on Friday, and when they hadn't arrived by 6:30, we were worried. I had to call you to find out that your plans had changed - and you both knew this since Thursday."
Joshua (your son) responds: "Mom, I'm sorry. I thought Allie was calling you, and she thought I was calling you, and it just got lost in the shuffle - we're so busy, and when the plans changed, it was kind of last-minute, so I'm sorry for that."
You: "I get that this time was a mixup, but it's happened before, and the thing is, it seems Allison never really ends up calling us when plans change - what ends up happening is that I call you to find out what is going on. This is very inconsiderate, Josh, and you know that. Dad and I have our lives, too, and we're busy, too. We cleared our schedule last weekend so that the kids could come and stay, and Dad turned down an invitation to go fishing with friends. In the future, I would like you to call at least a day ahead if plans change - but definitely, I would like you to be the one to handle it, rather than trusting that Allison will call. I don't want to be the nasty Mother-in-law, causing problems with your wife. But I also don't want to be left hanging, and whether it's intentional or not - that makes me feel like a doormat. So can we agree that in the future, if plans change and you are backing out, you will call, not Allison?"
Example 2: You have the opposite problem - Allison drops over and wants to leave the kids with you constantly, leaving you little to no time to yourself, and treating you like the hired help and her personal babysitting service - at her beck and call.
You: "Allison, I'm sorry - I can't take the kids just now."
Allison: "Oh, I know it's short notice (really, it's no notice) but please, please, please - I have this thing..." (as she shoves the kid toward the door)
You: (standing resolutely in the doorway) Honey, I'm sorry, I can't do it this time. I would love to, but I really do need some notice. I have plans that I cannot cancel, and I can't take the kids with me."
Do not weaken to "keep peace." It won't work. She will continue to do this, and you will continue to seethe with anger - and in the end, you may blow up and say something unfortunate which will cause a huge rift in your family. Instead, hold your ground kindly, but firmly, and set this boundary clearly. Later, call your son:
You: "I guess Allison told you I was "mean" today, and couldn't babysit."
Josh: "Yeah." (he probably understands and is not mad at you, but is exasperated that his wife is having a cow about it and doesn't know how to get her off your case)
You: "I do feel bad about it, but honey, I have a life, too, and lately it really feels like Allison just assumes I will be able to take the kids whenever she feels like going shopping with friends or whatever it is she does. I don't appreciate being taken for granted. I don't want to cause World War III here, and I don't want to hurt her feelings - I love the kids, and I always want to spend time with them, but, Josh, I need a little notice. A little appreciation for the fact that it's not easy for me taking care of little kids - as much as I love them, I'm getting older. I raised my kids and I think I deserve at least the respect of being asked first whether I might be available to babysit, rather than just having them dumped on me. Can you speak to her, please? I think she'd take this better coming from you - but in the future, I really would like for her to call. Even if it's just a couple of hours ahead, at least having the option to say yes or no would make me feel a lot better."
Again, no matter how clueless and rude you believe Allison has been, it's better to simply deal with your feelings about it rather than criticizing her. Josh will understand, certainly, and if you can get him to talk to his wife rather than leaving it up to you to keep on saying no to her, it will smooth things between you. However - if Josh does try, and it is to no avail because his wife is just one of those people who feels entitled to do whatever she wants no matter how much it inconveniences others, then you will simply have to set your boundary hard and not deviate from it. One suggestion: Never babysit unless you receive 24 hours notice first - but make sure both Josh and Allison are aware of this. State that you have a life of your own and if you are asked a day ahead, you very well may be available to babysit, but past that, you will not be able to. In other words, if she calls and asks for you to babysit an hour from now, you simply say you've already made other plans. If you stand firm on this and don't just allow her to steamroll you, but rather, patiently and calmly just inform her without explaining excessively, she will soon learn that she can't expect this of you.
Accept the reality of the situation. If your son has children with this woman, no matter what you think of her, the children need their mother. Trying to drive a wedge between them and their mom will only drive a wedge between you and your son - and his kids. Instead, just come to terms with this: she may not be the daughter-in-law you dreamed of, but she is the daughter-in-law that you have. Choose to have whatever relationship is possible with her, for the sake of keeping contact with your son and grandchildren.
Make nice, if all else fails. If you know this girl to be vain, flatter her. If you know she gossips, just find some other place to be so that you don't have to get involved in it. If she swears and this offends you, never call her on it in her home - but you may ask her to tone it down in yours. If she is overly critical of your cooking, your decorating sense, your clothes, just blow it off. Learn how to Deal With Impossible People. Listen politely and very carefully to what she says, and then go and do exactly as you please. If she's just difficult, this may be the best you can hope for. If she's dangerous - that's another story (example: the reason she's difficult at times is that she's a drunk, drug addict, etc.) and you really should contact Child Protective Services (or its equivalent) in a case like that.
Go with the flow. Learn How to Be Laid Back. There's no payoff in constantly complaining to your son about her. If you've expressed your feelings, made your boundaries clear, and asked your son to intervene, all with little to no positive outcome, then just go with the flow. All you can do is not allow her to run over you constantly with unreasonable expectations for babysitting services, etc., and if she's a nasty little sniper that makes critical or snide comments, just blow them off. And never say anything critical or nasty about her to your grandchildren - she is their mother, and no matter how much you may wish it were otherwise, Mom always trumps Grandma, at least until the kids are mature enough to see their mother for the difficult, confusing, narcissistic person she is. Just try to get along for the sake of the kids, so that you can be an influence for stability and compassion in their lives, and hopefully thereby mitigate some of the damage she is doing to them.
A positive attitude and a willingness to make the best of whatever situation comes your way with this woman will help you in the long run.
Refuse to gnash your teeth for hours after she makes a snide or callous remark. Remember that her mean remarks say much more about her than they do about you.
Try not to take it out on your son.
Accept that some people are just like oil and water - they just don't mix well. That may not be because she's cold-hearted, or vice-versa. It may just be that your personalities don't mesh well. Everybody doesn't like someone. If you can simply accept that she's never going to be your favorite person and try to appreciate those moments that you can enjoy with her, you will cope better.
Do realize that it may be that she is shy, has her own trust issues, or is over-eager to feel a family-type acceptance, and in that eagerness, may overstep normal boundaries. This may feel like a bone of contention, but in reality, it may smooth out over time as she feels more welcome and part of the family. If you have been welcoming, but have been rebuffed, continue to extend that hand of welcome until she is able to take it as a peer, and not as an overbearing, out of control child, or as a cold, remote, or disdainful stranger.
Simply realizing that you cannot change her - you can only change your response to her - can be very freeing.
Any harsh remarks that you make to her will not sit well with your son. Temper, temper.
Frustration with her will probably be a way of life. If you can try to "reset" each time you see her - in other words, clean the slate and see her as blank every single time - then you won't be holding old grudges or nursing old disappointments and keeping a running tally of them in your heart.