Can't move on

I've been into a relationship of 5 years everything was so good for 3 years until my boyfriend joined university. Tho i had no issue with him making female friends but from the very start i had this fear of losing him which i would tell quite often. Many girls came and went away but as time passed i became so insecure about our relationship. We would fight on such issues but he would always tell me that there is no one except me in his life. Everything was so beautiful but then he met this girl from his class. They became good friends. Even i liked the girl as well. I had no issue with him being friends with her. Until the girl started to feel for him. My boyfriend doubted that and i told him to tell the girl about us so she wouldn't expect much and would step back. Not once not twice i told him 1000 times to just give that girl a hint that hes with me ( our relationship was quite a secret and no one knew about it except for few friends). But he didnt tell her due to which we used have constant fights. We broke up last year and i became a mess but he came back and said we should talk about this in our homes and get married. I told my parents but he didnt. He said he would but he didnt. As time passed we had more fights, he never told that girl about me. On and off my boyfriend would tell me that that girl is very nice and how should i tell her that i like her. I always thought hes joking around but he never. It would break me up into pieces whenever he used to meet her and talk about her. He knew i was getting hurt. He knew how much i hated that girl. Still he didnt do anything about it. Recently they both confessed their feelings and we broke up. I hate this life. I've done so much for him. I loved him so much. According to him we were very different and he used to tell me that I'm too immature and that i dont understand him. I do agree we had differences but i always thought that we should accept eachother the way we are inorder for our relation to flourish but he never understood this. I did everything for him. I cant get over him. Hes always on my mind. I cry so much everytime i think about him. We had planned to marry. We had to make so many memories together. I don't like anyone except him. He was the kind of man i always wanted. I cant imagine being with someone else. My ex and his friend will soon get engaged. I don't know what to do. I was always so possessive about him. My brain isnt functioning properly. Please tell me how to move on. Its soo hard seeing him with someone esle. I'm so hurt