My mother is a bully much like your in-laws. After my miscarriage, she told me "It wasn't even a real baby yet so stop being so dramatic." When I was facing a marital crisis and mistakenly thought that it was time to tell her what was going on, she spread despicable rumors about me. My relationship with her has been a series of betrayals interspersed with little insults, and when I show upset, she finds a way to blame it on me.
I've healed and become a better person despite her hurtfulness. What works for me is--as many other posters mentioned--polite distance. I don't share with her anything more than I would share with a casual acquaintance. When I have to chitchat with her I'll talk about my cat's latest antics or my son's new achievement, but my #1 rule is do not give her any ammunition. Do not share anything that can be used against me.
IMO, this is the route you need to go with your in-laws. Pretend they're a next-door neighbor or a distant cousin. Pretend they're a long-forgotten acquaintance with whom you are chatting at the grocery store. Don't make any more effort for them than you would a near-stranger. If you want to cook a nice dinner, concentrate on your enjoyment of it and don't expect any compliments from them.
You can even list things, in your mind beforehand, that are safe subjects. So when they ask you what's going on in your life, you can tell them about a book you read or a new coworker. When they ask you personal questions, give them a non-answer and change the subject. Eventually they'll get used to it, and so will you, and it won't be as much effort.
And lest you think that this is a sad and unfulfilling way to live, I find it quite freeing. There's a lot of security in knowing that they can't hurt you anymore. Once you get into the pattern of treating them with passing superficiality, it feels more natural and comfortable, and you may even enjoy your relationship with them again.