Well, As sad as it is... I think its a safe assumption that she won't be in your wedding party.
I would say she is probably embarassed, and feeling bad, so its easier for her to just not deal with it then to get a backbone and be honest with you.
Its such a hard thing to deal with, and it seems like your not the only one who has bridesmade trouble after reading some posts... all I can say is.. you dont need anymore stress... plan your day how you need to and hope she calls or at least shows for your wedding day as a guest.
Sorry you have to go through this...
Rachel