Part of me feels sorry for her as a victim of her circumstances and also sorry that I wasn't there for her in the right way.
This woman has cheated on you with (at least) THREE different men. She has LIED to you over and over again. She is a LYING CHEATER. I'm sorry if that sounds harsh but you need a good cold slap to the face of what you are up against. She may have been a victim of abuse in her past but that in NO WAY excuses her current behavior. And no, she is not a lying cheater because you weren't there for her "in the right way". You have the worst kind of wayward on your hands and appeasing her is only going to send her further down the rabbit hole. Your best chance of success is to take a "tough love" approach and take it right away. Ironically the smartest thing you've done in all of this is to tell her to pack up and get out, but unfortunately you didn't stick to your guns. That would have gone a long ways towards waking her up to the fact that her behavior is WRONG and will not be tolerated by you.