Getting my boyfriend back

I need help! I dated a boy for over a year and I loved him and I broke up with him - now he's apprehensive about getting back with me. We have been broken up for about five weeks- and he has been "hooking up" with this new girl. I really need him back and he told me he still cares about me. It's just so complicated I've resolved to asking you guys who I don't even know! Any help or anything I can do to prove that I can make him happier would be a great big help