Need Advice...Please Help...:/?

I recently broke up with this guy that I was in love with. We broke up because we kept arguing over and over again. He was really inattentive, oblivious, and selfish but he did try to make me happy and make us work. And now he really wants to be with friends but I can't be friends with him because there is so much emotion involved. But my question is why am I so angry at him? I want to be his friend but whenever I see him, I always get so angry and I can't figure out why...please help. If you need more info just ask. Thanks in advance...