My boyfriend is too obsessive

My boyfriend and I are together for 2 years and 7 months. Everything was almost fine, until we both got in college. I fell in love with someone and I think he liked me too. We were having a lot of fun, but I know we weren't go any further. I love my boyfriend I didn't want to do him harm. But in time he found out that I like him and he forbbid me from talking to him, writing to him and stuffs like those. Once I couldn't help myself from not writing to him and I did, my boyfriend find out about that and wanted to break up with me. I understand that but I asked for one last chance.So he gave it to me, but have lost his trust. Wel we are fine now, as far as he is concerned, but me I'm alone with no contacts, because of him, and also hurt because I can't see the guy I'm stupidly in love with, which HE doesn't know anymore, because I told him that I wasn't anymore. But if I want to talk to him, to see him, which I'm not sure he would want, but still. .. I won't be able, because mu boyfriend won't let me ... And I'm going crazy already, I can't live like this anymore, and I can't live without my boyfriend either ... :( So I have no idea what to do. The idea was for me to make some friendships in here with my colleagues, so I can go out with them like a normal person who is 19 years old and have one nice and strong realationship with my boyfriend. Instead I have something like a realationship, where I'm just a housewife, not going anywhere, only going out with him and ... just a loner ... Which I never wanted it to be... So can someone tell me what to do?

Don't get tied down with him if he is making you unhappy, and unable to really enjoy your college life. If you are worrying about stuff like this all the time, it is likely to affect the outcome of your studies (your grades will suffer).