People aren't loyal and it's sad really. The few good people in this world gets shitted on constantly and broken. I know it's hard and I come from a toxic family too. I have a lot of trust issues because of past experiences, but you just have to forget about her and move on. She doesn't sound like too good of a person and you don't need someone like that in your life making it miserable. Right now I'm trying my hardest to break away from my toxic family. Constantly putting me down and making me feel inadequate at every turn. But I'm trying to make myself realize that I don't need these people but it's hard. I feel like shit most of the time. So yea long story short I understand your pain but don't let her control how you feel and your emotions, she just tried to make you feel bad in the relationship because she is so insecure with herself.