Back story: I've been married to DH for 10 years.
Over the past 5 or so years, my relationship with SIL has deteriorated. She has said a number of inappropriate things to me, which I initially laughed off, but each time I see her she uses every opportunity to take a dig. These digs have mounted up and now I actively avoid her as much as possible and do not make contact with her. The best thing I've found is not to give her access to me to enable her to get her digs in.
The last time I saw her was a few months ago and after a number of acerbic comments made to me, I had a heart to heart with DH and told him how I felt just being around her. I have said that for him I will always be polite, but that is as far as things will go and I have no interest in meeting up with her socially or to go for drinks with her (she is usually worse when she's had a few to drink).
DH thinks I am blowing things out of proportion and each time she crops up in conversation it feels like he takes her side by telling me she doesn't have an issue with me and it's me that has the issue with her etc. Today a card arrived in the post, addressed to DD from her cousin. I didn't say anything, but DH immediately said don't worry there won't be any appropriate messages in it for DD (she has previously said things to DD that have been repeated back).
He didn't need to say anything and it immediately gets my back up. He doesn't seem to grasp why I feel the way I do and I am fed up of feeling as though she can do no wrong where he is concerned. It's causing problems in our marriage and I don't know how to handle this without getting emotional with him.