I'm in love with my ex-boyfriend, what should I do?

I would say what you miss may just be your friendship with him. I would start working on getting that back with him by saying stuff like I hope we can go back to being good friends. It is doubtful though it will later develop back into a relationship but just start hanging out with him more and he may realize he misses your relationship. First focus on friendship and then there may be love. Good luck!