Sounds like you are in a little bit of a jam. There are a few different things you could do to resolve the problem. One would be to have someone replace her. This can be a delicate conversation to have. If she is beginning to plan her own wedding, you could simply say, "[Friends name], I don't want your being in my wedding to be a burden or to interfere with you planning your special day. If it's too much for you right now, I can ask someone else. I still want you to be apart of my special day...(offer a smaller part to her potentially)." She may be seriously stressing out about trying to (from her perspective) plan two weddings. Her mentioning a car wreck and acting distant might be her trying to hint at this. Replacing her might actually be a relief for her.
Another route would be to add another Maid or Matron of Honor. This would be someone you can count on to take on the duties tied to this position.
Either way, approach your friend with respect and let them in on what you're thinking. This person is someone you believed to be one of your closest confidants. Every relationship has it's bumps. The key to getting through them is communication.
Good luck!
