I think she may well need help, but it really is not your responsibility to help her, especially if you do not have the emotional capabilities right now. If you want to be her friend and see her, maybe ensure it is only in the type of environment where she cannot snap or you cannot discuss too personal issues e.g. go see a movie, go to a concert, lunch with a whole of people...

And then the next best thing is to get to her see a T - even if it means practicing tough love

Hang in there, and I hope you have your old friend back soon!