I'm having a lot of trouble with my sister. When I'm not around, she tells everyone how much she loves my fiance and how great we are together. But, she & I have had a lot of tension over the last few years and she clams up and acts so cold whenever we're around. I asked her to be a bridesmaid over a year ago, when we first got engaged, but I'm having second thoughts now. My fiance doesn't like her because of the way she's acted every time they've met and doesn't trust her to be "good" at the wedding (she's basically ruined my last 3 birthday parties by acting so cold to all my friends). I'm not particularly happy with her either, but a) she's my sister, and b) I've already asked. What do I do?! How can I explain to her how I feel without making things worse?