text: You're not engaged (yet)...so there's really no reason to worry (as of yet).  Once you are, you ask who YOU want and obviously you don't ask this friend.  If she's hurt and disappears from your life over it, she is not a REAL/TRUE friend.  I know what this is like as I am engaged and I watched a friend have to have 2 maids of honor because her cousin believed she was THE maid of honor the way your friend believes she is going to be a bridesmaid and my friend was miserable on her wedding day because of it!  That is the other part to consider, IT'S GOING TO BE YOUR DAY, ALL ABOUT Y-O-U...it's just about the only day in your life when it will be "OK" to be as selfish and/or self-absorbed as you possibly want..within clear reason of course...after all, half the day will belong to your fiance, too! ;)  Seriously, if you don't want her in, don't ask her.  If she still persists, tell her again bluntly...if that doesn't work I really don't know any other nice way to put it.  She can go on in her dream world...but without you telling her which dress, color and other need-to-know details surrounding bridesmaid-land, she'll never be able to pull off her own fantasy.  Hope this helps.