I'm really getting nervous about my FSIL and the wedding.. any advice?

I really don't understand why she is in the wedding. I would never allow this. And if my fiance didn't back me up and say, yeah this behavior has gotten out of control, she shouldn't be in the wedding, well then we either wouldn't be having a wedding or we wouldn't be getting married at all. I guess I am just a low-drama, hassle free person who doesn't put up with this kind of bull crap. Look at all the energy you are wasting on this one person. Buying a book, having to ask friends and family to basically babysit her during your wedding. Really? Ridiculous. Just tell her she isn't a bridesmaid anymore and ignore her calls asking about wedding stuff. Really, too much time wasted on this, makes me think maybe the drama is a little bit, enticing? Otherwise why would you even put up with this???