What to do, what to do...

What's a girl to do with the most selfish "friend" she's ever known?

This may come out all wrong. I'm all kinds of angry and frustrated which may very well jumble everything up.

I have a friend. She sucks at being my friend. I'm not sure when the last time was that she asked me how I was doing or how Brian was. Everyone asks me those questions. Even people I don't know very well will ask me those questions. She never does. She can't stand silence so she fills every potentially quiet moment with rambling sentences about herself. She calls me and dumps her relationship problems on me. I can't count how many times in the last 6 months she has called me crying. Yet, she expects me to be happy for her when she forgives him over and over. I don't see all the good things that may (or may not) be happening and she doesn't realize this. I thought he was a nice guy when I met him, but he could very easily be a messed up abusive sleazoid. I am supposed to stand next to her in 3 months at her wedding. I already bought the dress ($125 not counting shoes). If she dumps much more relationship drama on me I'm not sure how I'll be able to stand there supporting her union in good conscience. Plus, you aren't supposed to deal with your relationship problems outside your relationship. That's just asking for problems. Apparently her mother didn't teach her this like mine did. I am so overwhelmed with frustration over this. I wish I could just let it go. I'm going to try to let it go, but I'm not sure how easy that will be. I'm tired of feeling used and taken advantage of. If I didn't have money invested in a wedding in 3 months I think I'd start cutting the friendship strings now. Instead I have to suffer until the end of September. I may need to scream into some pillows and punch some trees. I don't know what to do.

S.