READ IT AND ADVISE! should I stick around and be treated like this?

my ‘so called’ best friend for 7 years has done the most horrible thing ever to me. if your best friends with someone would you would explain and tell all the secrets, things you did and they put it out on a plate for your ex boyfriend. she told her ex everything about me. is that wise? basically I’ve have been close with my mate for 7 years, and I would tell her everything, tonight just found out all the things I told her,she told her ex boyfriend. me and her ex have become quite close in friend wise because I felt so sorry for him by the way she treated him, had sex with someone else in some woods while with him and then dump him for the guy, only to be done the same by that person she dump her ex for. her ex proper fell head over heels with her, came over at 3am in the morning to see she was okay after that he finds she with the guy she cheated on with him and staying at his house the night after there big chat. now he feels totally fuc*ed over and so do I. she would not just tell him all my personal things but insult me too for doing them. I did like everything for her. I would make effort for her when she was upset. let her stay when she had a bad time at home. I would arrange dates to meet up. she puts friends she met about 2 months rather than her childhood mate. one time the day before my birthday I wanted to have a few drinks and asked her to come over because everyone else was busy but instead she was staying with ‘another boy’ because they arranged a movie night. the only person I had that night was my boyfriend. why would you cancel on your best friend? can I even call her my best mate. I dont what to do. im not the type of person to just argue. but I dont think I can EVER trust her again I actaully did quite a lot for her. and im so upset and angry, is she even worth anything. does she deserve what she gets? what goes around comes around. any thoughts? all I get in return is nothing, she so selfish and part of the is because she was bought up spoit. she even treats her poor nan of 80 years old like utter crap, its alwul.