This is coming from someone who was once the woman in these situations, all I can say is get her committed or get her to see someone ASAP. When I was in that state, all I wanted was for someone to look after me. I didn't care what kind of help it was. I'm not saying she's the same, but this may be a cry for help from someone who's hit rock bottom and doesn't know what to do or how to express herself.

The longer you're in contact with her and the longer you continue to feed into her manipulative ways, the more dangerous she will become to herself and others.

I am honestly so sorry that you have experienced this. I wish you and her all the best and I hope she can get better.