my ex doesnt want me happy?

my ex boyfriend doesnt want to see me happy....i was happy talking to his friend but we were just talking as friends then he ruins me and his friendship becuase he said i was using him to get back at him when that wasnt even the case. I dont use ppl like him..it's like he wants me to be miserable without him. he doesnt want me happy . he should feel pitty the fact that he cheated on me, he never apologized but it is what it is..he shouldnt have feelings for me and he said it itself that he doesnt anymore. but yet you intefere with a friendship i had with your friend. its like he dont want to be happy talking to a guy friend especially that he knows. hes so confusing and the most heartless boy i've ever met in my life. . he left me with no answer to why he chose to cheat on me and treat me so horribly..I have moved on but its like i need answers not just "move on" but as to why he did those actions . kind of like a thesis statement as to why you think he done what he did...Give me the best answer Possible pleease and thank you.. Oh and im 17 i lost my virgnity to him we got in a fight the night i found out he cheated on me i hit him and we just fell out every since October 13. two months ago. and it I have to see his face almost everyday in second period its like hes happy but doesnt want me to be happy. when im not the one who did anything wrong..so Why is this happening any background knowlegde?