I think what makes IL problems even worse is the holidays because you're blasted with all the commercials, songs, etc. about family, and everybody getting along and having a good time, and face it---there are a LOT of us with lousy in-laws.
My ILs fit right in with the "outlaws." DH has 2 brothers and 2 sisters; MIL has her 2 favorites, and it's kind of funny because they both are blonde, the other 3 "black sheep" have black hair. Needless to say, DH is NOT one of MIL's favorites, even though we're the only ones who live near MIL. She only calls DH when she wants something. Used to hear from her a lot when she was living in her house and needed things fixed, but now that she moved into an apartment, we don't hear from her at all.
Things were ok when DH and I were dating, but once we got married, MIL's attitude changed. I was the first non-Catholic to marry into the family. I was the only one to continue working when our DS's were born. I am also very up front and open with people, where DH's family doesn't talk about stuff at all. My family, we yell, tease, get it all out and everybody's fine. DH's family puts on an "act" all the time.
There are tons of things that have happened over the years, but this past summer, they planned a family reunion. MIL called to tell us about it; DH and our youngest DS were planning to go, but our oldest DS had an activity so he and I were missing it. Well, we got a call from MIL that the date was changed, but she didn't know the new date. Weeks went by and we heard nothing from anyone. A casual mention in an e-mail from DH's brother (also a black sheep) about the new date is the only way we learned the new date. Luckily, we had plans and couldn't make it anyway, but no one bothered to tell us the new date.
Then MIL calls a couple of weeks ago, laying the guilt trip on DH. Isn't it amazing that after all the crap they pull on you, they can still make you feel guilty because they're "family"? We live the closest to MIL (only a 45-min drive), and yet we haven't seen her since Jan. of 2002. Sad.
Ok, end of venting. This thread is very therapeutic.