What do you think I should do now?

I think he is using you and I think you realise that too. He was getting stuff from you (time, food, sexual favours) without having to split from his girlfriend who he clearly likes better than you or he'd be with you and you alone. What kind of guy treats his girlfriend like that? Someone you'd like to be with? It's not your responsibility to get him to summer school. You are making excuses to get in touch with him and you will end up getting hurt. Distance yourself from him and explain that you don't want to be involved with a guy who is taken. Then find someone new to hang out with.