cheetahcub

Family is very important to all of us, but you and your hub comes first.
It sounds to me that your husband is the only one that can sort this one out. He shouldn't allow it to go further. If you're not welcome, he's not welcome, and he's not going without you. Unfortunetely, it seems that he hasn't realised this. Being stuck between your family and your wife is not nice at all, and must be killing him, because they seem close. But you should openly discuss the way it makes you feel.

If he confronts his sister, saying that he won't budge if she doesn't change her act, the result would be that she'll say sorry. If she doesn't, there is nothing to do but stay away from there for a while.

When you have to go to birthdays, weddings and so on, be yourself, be helpful in the kitchen, be friendly and ignore her flat, from entering to going. Keep your chin up, she's got issues, not you. Be the better person, for your husband's sake.