Any one going tru a break up ..i need help plzz?

My girl let mi go ,making me feel so bad and hurt . She told me some thing she did behind my back while I was at work thinking about her . I gave her all my love I was a good boyfriend I never did nothing hurt her feelings. In the other hand she broke up n just call me everyday just make me feel bad idk why she was doing that she was acting like a diffrent person ,so I stop answer the phone but my feeling got over me and one more last time I answer the phone and one more last time she said mean stuff to me and in the background I heard people luaghing and she told me she was meeting up with a new guy at the mall ...crust the last pieces I had left of my heart how can I move on with so much pain... now I feel alone and hurt ..idk what I did wrong