Ex-Boyfriend Back to Boyfriend

I've been single for almost 9 months and lately I've been spending a lot of time with an ex boyfriend from high school, we've also been intimate. Last night I went to a family party of his and he looked so happy to see me there with him, before I left he confessed he liked the fact we were really close to each other again and that he doesn't mind at all is being intimate and only being friends, but he would really like if I accepted to be his girlfriend once again. He told he wanted me to really think about it and doesn't want to force into a relationship if I don't want it. What should I do, I do feel something for him but I feel like I still haven't had closure from my past relationship.