Best friend dating ex boyfriend

My ex-best friend is dating my ex-boyfriend and I don’t know what to do. I like my ex-boyfriend again and sometimes I wonder if he likes me back, he acts like he does but he’s still mad at me over our break up. We talk and stuff and he used to be mean to me and now he’s starting to be nicer to me. We used to be best friends as well and I don’t want to lose him completely. What do I do?!? I don’t want to start off the school year with drama with my ex.