At some level she believes her own lies but only emotionally. If she thinks bad thoughts about you, then you become bad to her and you no longer have any positive attributes according to her. That's when she will go from your friend to your enemy and start lying about you to make you look bad. If hardly anyone believes her then you are in a good position. It may hold her in check slightly if she has no one to manipulate. But still I'm convinced they all know very well they are lying, it makes them think of themselves as "evil" or whatever, they know it will hurt you but and they all claim to feel guilty about abusing you but it never stops them from doing it. Abuse is abuse, it doesn't matter if these women pretend to feel guilty or not, what they are doing is wrong and they know it, they know the difference between right and wrong, they are not insane.
If you can convince the people who know you and her both that she is just trying to manipulate them and abusing you, you have nothing to worry about it, but I understand it's hurtful and unpleasant. Just try to stand the high ground and don't stoop to her level. You'll feel better about yourself.