What to do in this case?

i was with this guy for 7 months..at first it was amazing he went to a university and turned 21 and completely flipped...he became distant with me...school interfered with us seeing each other so we only saw each other on weekends...that lead to arguements etc..he broke up with me...after a week he said he wasnt in love with me but he still loved me i got pissed cuz i gave so much in the relationship and let all my guard down and this *** did this to me. found out not so long ago hes getting to know this girl and he has feelings for her...no wonder he stopped loving me so quick! i got so upset last time i spoke to him ended up insulting the **** out of him. took me time but i deleted him from fb cuz the pics wit this new girl were just horrible to me. i am currently seeing a therapist cuz this is so ard for me. what can i do to stop feeling such resentment? i keep dreaming bout him and waking up anxious and can barely sleep...i take pills like advil or 3 benadryl to get drowsy...yeah he probably wasnt right for me but even though i dont hate him i have so much anger and it is not nice to fill my heart wit this feelings...what can i do to forget bout him?