Is my relationship worth it?or should it stay dead?

I've been with this girl for 2 years almost. I can say I've always been crazy for her and loved her a lot, despite the fact I couldn't show it to her. Our story was AMAZING. I was really happy for 8 months.
Once she met a new guy friend that was really down on her, this is what happened = She lied to me about going out with her girlfriend to go to dinner with him.- I broke up with her, and her best buddy told me about her past and how she cheated on her previous bfs etc.Eventually love was stronger, so i wanted her back, but i had to live trough knowing they were always together at school, and always hanging out/ her going to his house.- That guy ended up kissing her, wich i found out by snoopin trough her ipad.- My condition to stay with her, was to her never speak to that guy again, and tell him off for disrespecting our relationship… But she set it all up, playings rolls with him to fool me. She eventually stoped talking to him, till one day i came to her class and caught them sitting together laughing… So i left again and she promised to never speak to him, and to give me time to get the trust back, on the condition she never lies to me again… One day, she left her fb open on my laptop so i went on it… She was talking to this guy (B) and everytime i asked her what she was doing, she said " nothing ". When i asked her to screenshot her fb, she deleted that convo and sent me a picture.today we broke up, but she added back all the boys back in contacts.

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