need your advise

You have been a good and loyal friend, and now, you, yourself, are at the breaking point. It really doesn't matter if she has multiple personalities or some other psychiatric condition. You are not a doctor, and you can't fix her. In your place, I would work on getting my own emotional strength back, and then if you want to resume contact with her, fine. If you don't, fine. You might gently tell her that you are under a doctor's care yourself and won't be able to see her for a while and then retreat from the situation. Good luck to you both.