You sound like you want to hold on to this relationship. But it's definitely hurting you. If she is physically assaulting you as well as slandering your character, you may be best to remove yourself from the situation. You can commit yourself to a marraige but if the other partner is not committed it simply will not work. You may need to save yourself and find some spiritual counseling to get yourself to a better place.
The use of VAWA does not put you in legal danger because USCIS does not prosecute. The assault and battery charges that she placed against you when she had you arrested could lead to a records so you should find out where you stand on that and get a lawyer if need be. I definitely think it's best that you get out of the situation, because right now you're placing yourself in harms way and she doesn't seem to hesitate to use all her resources so you'd better move on.