What should i do about my maid of honor?

Its kind of a long story. My maid of honor has been my best friend for 14 years and we've never had a fight until recently. She is having her first serious relationship that happens to be crumbling beneath her.. But a few weeks ago she accused me of making my facebook status about her and said boy. Now I know that this is brought on by her roommate because she HATES that she isnt the so-called-best-friend. But it turned into this huge thing where she told me she didnt want to talk to me ever again and threw every mistake in the passed 14 years in my face. Well the things on facebook were NEVER about her, and even as she bashed me to the core i couldn't bring myself to throw her mistakes at her or even call her a name. I just sat there hurt and shocked. Well since then she has apologized, so i thought everything would go back to normal.. I was wrong the situation with the boy has gotten much much worse and she is ignoring me now. I just don't know what to do. I'm so hurt by what is happening and i can't imagine someone else being my maid of honor. Plus i can't get over how immature the argument was. Her sister and mother are both very special people in my life as well and her sister is also a bridesmaid and they both are helping out while my MOH has yet to do anything! To me i sound selfish, but to my fiance he says my MOH is supposed to be there and supportive. and im getting more and more frustrated because if she said sorry and admitted she was wrong i forgave her then what is going on now? i have asked her sister if she thinks my MOH still wants to be my MOH and she said she is sure of it.. then whats with the ignoring? i dont want to involve the sister or the mother because its between us two. But she wont answer calls, texts, facebook messages, nothing. what should i do? i feel like i'm being let down in a huge way, and i also think ignoring someone is really immature. HELP