I want to just say I hope that you know you are the one holding the truth. what she or anyone else says is meaningless. I know that is a small comfort in your situation. I know my advice to you has been to leave but just as each that have replied, we give answers from our own experience and worldview. for me my fear and anger have brought me rage a LOT and it terrifies me me still because I know how it can so quickly go to a place I cant manage it. I totally understand how it came to that situation and I feel so sorry that you have that now to deal with too. I understand how frustrating it must be. I hold to my advice man leave her completely alone. there is not much chance of healing or any positive thing happening as long as you are not in a healthy place. and I still think the situation can only become worse if you try to let her get close again. she lied the first time,and sold your family on that lie there is no reason to think that her behavior has changed at all. she could cause you a lot of pain man as it seems you are having a hard time even just knowing she is there. I hope that you can just find a way to live your own life and not let her become a part of it.
Either I will find a way, or I will make one.