This is tough. You may want to talk to someone yourself who deals with behaviors in order to help you to end this, or to deal with it in a way that keeps her responsible for her own behaviors, and does not cause you to be so distraught. Likely, you will need to end the relationship but you have to be okay with risks which is where someone can help you. She may possibly hurt herself, but it is something she needs to deal with----as much as she experiences that as impossible right now. She will more than likely survive, and may grow...
All adults need to be able to care for themselves emotionally before they are able to care for others in a real sense. This is not about you, and would be triggered by another intimate relationship.
I don't know if she could tell you, or if you know, how she was able to remain, apparently, in control the first couple of years...