Maid of honor drama

I knew from the start that choosing this girl to be my maid of honor would come along with some drama. I think everyone knows someone like this...theres aaaaalways some drama going on in their life... But ive known her since I was 5 and she chose me to be her maid of honor in her wedding (which was cancelled)
The little things that were annoying were she woulddnt give me her measurements for a month and I had to beg her bc i was at the deadline of having to rush order all the girls dresses. She still hasent given me the money for her dress (which was purchased in march) and i put 100.00 toward it, She hasent helped in any way for the wedding, bridal shower (didnt even rsvp for it) and has not planned any plans for a bachelorette party....but whatever I can overlook those things.

2 days ago she drops a bomb on me that she MIGHT not be able to make it to my wedding because she has a surgery planned. At first im totally understanding and sympathetic of the situation. I would never expect someone to put off surgery for my wedding. BUT then she is telling me shes postponing her surgery (which she could get soon) so she can take a vacation with her boyfriend. and while shes talking about it I realize that shes known about this surgery for weeks and didnt even tell me...and she told me she explained to her dr how important it was for her to take a vacation with her boyfriend (a vacation that is not booked or anything) and didnt even mention my wedding. When i try to ask her details about the surgery and when she will know the details, she leaves me in the dark. She texts me the next day 'When is your wedding? My bfs sisters wedding might be the same day and I might not be able to make anything'. Like ***? After I asked her if she was saying she thought her bfs sisters wedding was more important than mine, she made up some lame exuse about needing her bf to be there to help her for my wedding...

Ive paid for her MOH dress which is a size 16 which couldnt fit any of the other girls, so serious alterations will need to be made asap. her name is in programs, bouquet is paid for, i paid for her hotel room and i will have to change ceremony details bc i'll have off numbered bridal party...

So now i have to ask another girl to be my bridesmaid 2 months before my wedding which is sooo awkward...and hope that she can fit in my other friends dress.. I went ahead and
already asked my bridesmaid to step up to be maid of honor (who i should have picked from the start)
When I told her I needed to replace her she totally changed her story and makes it sound like she can make it. She doesnt even know my wedding date when i talk to her, or my bridal shower date. But knows she can or cant make it? Its weird. And honestly im hurt, bc ive bent over backwards for this girl all my life. Shes driving me crazy. Sorry for this extremley lonnnng vent..but do u ladies think I did the right thing? I hope so.