Oh my, where to begin .... ?
SIL who told me "you might be his fiance but I'm his sister, one word from me and he'll drop you". She must still be trying to guess what that word is because I'm still here :)
MIL who, in the run up to our wedding, asked if FILs partner would be attending (they're seperated) and would she be sitting with the family? Yes and yes were the answers, she expected her new DP to be invited and to sit with her so the same was applied to FIL. She went mad, said she wasn't going, then went in the kitchen to throw plates at the wall.
Two days before the wedding she announced she was going to use it as an opportunity it to say her piece.
At the wedding she went table to table telling everyone how much of a bitch I am, that the marriage wouldn't last, and that she'd be the one left to pick up the pieces. She also went on and on and on that the tables for the food had been put in the wrong place and that my parents paying for the food was further evidence of how spoiled I was. Eventually my DM offered to take her out into the car park to "discuss" it :o
When SIL got pregnant a few months after I had a miscarriage she sent me texts saying that no one knew how to tell me and that I must promise not to "go mental" (I honestly wasn't bothered). Every time we saw them they went on about scans and appointments and how it would be wonderful to finally have a baby in the family. At Christmas she was going on about SILS pregnancy and asked me "wouldn't yours have been due around now?". Unknown to her, I was pregnant again and when we did tell her she said that she "knew" I'd get pregnant to steal the attention off SIL.
It got even worse once I had the baby but I need to leave for school pick up soon and, really, I could fill an entire thread!