Ok so first thing first she's a b... i mean a horrible person and well you should stop seeing her (as much as possible), there's a little nice "rule" that i set for myself (you can use it too if you want ), if a person betrays me i cut all ties with that said person so he/she can't betray/hurt me again (all that talk about second chances is bs for me) and this rule worked for me, now i have less friends but i know that i can rely on them (at least for now ), that said i'm a very cold/rational/logic person so this "rule" may be too difficult/unattractive for you. I hope that you can move on from her cuz you know there are more than 7 billion people in the world (and roughly half of them are female) so maybe (just maybe) you can find someone better.
Now i could talk about my problems but i don't have any (i had some in the past but thanks to my "rule" not anymore).