It sounds like her personality may be consistent with what we call a personality disorder. This person is very manipulative and even dangerous. They have a love hate relationship with their partner as there is no in between. Most of all they can con anyone with their in depth ability to be what they want them to be. No one believes who they really are but their partner. Life revolves around them. They are so manpulative that leaving is difficult. You can consult a lawyer to see what your rights are. That may be your best option. She isn't going to go quietly. You have to do whatever you can to leave this relationship.
In the meantime I would see if you can get the family seen by a psychologist. That would give you extra support in this situation. Then you have on record the issues at hand. Enlist any help from family that would help you end this. Begin to let them really know how bad things are.
You have to be creative and that means making any plans you can to go. Do this very discreetly. I wish there were better ways to end this but you have to know what your rights are and that will dictate what your actions are.
Please press accept