Sorry you don't think I'm worthy.

I'm in my friend's wedding this Saturday and have been bemoaning the wearing of the bridesmaid's dress. Its not ugly or anything, its just one boob (not both mind you) won't fit in the bodice. So we went looking for a different dress yesterday. The dresses aren't all the same just the same color so getting a different one isn't too big of a deal. Well we could find none the specific color red she wanted. So she starts freaking and going "wait no its okay, lets just find similar, the maid of honor can be dressed a little different from the others."
I had no idea I was maid of honor, and apparently the other bridesmaid who was with us didn't know either. I have only met the other bridesmaid a handful of times, but I know she's really close to my friend. This lady and I have been getting along fine, but all the sudden she's giving me ugly looks and the cold shoulder, I can only guess because Emily said I was the maid of honor. I thought she just wasn't having one, but it turns out she just wasn't going to tell anyone until rehearsal Friday night so that people wouldn't be pressuring her into picking who they thought it should be. And I'll admit when she called and asked me to be a bridesmaid I was a little hurt at the idea that she picked someone else to be maid of honor. I mean I've been her best friend for 17 years. But I figured if she was picking someone else she had a good reason.
Now I'm ridiculously happy, but also at the same time I'm really worried. All the other bridesmaids are a really close group of friends that I never really got to know and like, and I know most of them don't really like me. They always thought I was a bad influence, and some other nasty things I won't repeat. I'm worried they might say something to Emily to make her feel bad, or act spiteful at the wedding and upset her day. When I casually mentioned to her that maybe someone else would be a more appropriate choice she looked at me and said "Trisha, you've been my best friend since we were in kindergarten, I never even consider anyone else and I don't want it to be anyone else." Which made the other lady with us even angrier. Now, other than just not wanting to wear the bridesmaid dress (we're back to the original, we're just going to get the bodice let out some), I don't want to go to the wedding. I don't want them trying to make me feel bad, or for them to make Emily feel bad. And Emily knowing me so well knew I would be thinking along these lines and called me this morning to say I'm not allowed to back out.