Is our friendship over or should i try to fix it again? plz help me!?

this girl and i've been friends for 7 months but i feel like i've known her my whole life or at least i did. within two weeks of knowing each other she told me all of the REALLY bad stuff about her family. i told her some of the stuff about my family and a couple weeks later i told her the rest of it. i have a really hard time trusting people so that was a really big step for me. anyway i told my sister about something my best freind had told me about her dad. i trusted my sister a lot at that point and she swore to me she wouldn't tell my mom. well the next day she told my mom but my mom was happy to know. she said it was ok and it helped her understand a lot of things. i told my best friend right away because i would never lie to her. so i told her and she wouldn't forgive me for two days. finally she forgave me because she needed me. i've ALWAYS been here for her and i felt horrible about what had all happened. so we moved ped it and became close again. well then all of a sudden she started hanging out with these three other girls like all the time. her and i only have 2 cles together so we would sit by each other at lunch and talk at recess. now she only sits by them and talks to them at recess and break. well on saturday i found out that she'd told those 3 girls something about my dad. i was SOOOO upset and when i talked to her about it she didn't even apologize. she said now i knew how she felt when i told my sister. i told my sister 3 months ago and i felt really bad about it. she didn't even care. she said she thinks it's ok cuz i told my sister so she can tell those girls about my dad. she was the best friend i've ever had but she's trashed me behind my back more than once. she's lied to me and whenever we get in a fight she finds a way to make it my fault. i've been crying almost non stop for the past 2 days. she's made me cry so many times before this and it takes a lot to make me cry. she totally ignores me when she's with those other 3 girls and now there are two more girls that she's really close with. it hurts me so much that she doesn't care. i love her and just can't believe this is happening. she said that she doesn't want to do this if i'm going to be all mad. dont i have the right to be mad? she told something really bad about my dad. she says it's not that bad bcuz it's not my worst secret. it's really close though. i'm scared that if her and i aren't friends that she'll tell people the rest of the stuff about my family (there is some REALLY REALLY bad stuff) and we write a lot of notes so i'm scared she'll show them to someone or "accidentally" let a teacher see. i don't know what to do. please help me!