So this guy....? Should I leave it? What in the world should i do?

So there is this guy . Yes he had me head over heels for him. I probably was fantasizing abit too much over him even though I didn't know him all too well. SO what did happen? Yes he was THE first guy I have ever liked. I can openly admit that for sure. I thought he liked me aswell.. He did admit to it once before but then something happened.. He was in a serious relationship a few months before meeting me. I thought he was over it... I have never been in a real relationship with anyone so basically he was my world. After talking to me for a few weeks we decided to go to the movies . Things went smoothly . Then he disappeared for a week and reappeared saying he had something to do with his ex. therefore his excuse for being busy. I havent heard from him ever since.. nearly been 4days ..He thought i moved on. So my question really is . What the hell should i do? I really liked him and i have no issue with his ex. I understand fully. Should i leave it? I like him still but i think i have no chance. I hate to think i was rebound..but in conclusion i really might have been so i don't have the esteem to fight for a guy who never really thought of me...