What to do About an Ex that Won't Make Up His Mind...

I dated my ex for 2 and a half years in highschool. We were inseperable and loved eachother very much, but it was a very complicated relationship with a lot of emotional strain. Now, we're going to the same college together, but we're broken up...obviously. Here's the thing. I broke up with my ex because I found out that he had made out with another girl twice when we were having problems. When I confronted him, he told me he didn't want a relationship with this girl. He liked her, he was attracted to her, but he didn't want to be involved with her. I broke up with him and left him an emotional wreck, and A WEEK later, he got into a relationship with this girl, claiming to be so in love and bla bla bla. I think it's stupid. He and I are in the west coast for college, and she's a sophomore in highschool on the east coast. At first, he was begging me to stay in his life, asking me to be friends, saying that I'm too important for him to lose. I told him that I didn't want to be friends until he told his girlfriend that we were speaking to eachother, because as far as she knows, we're not. I don't want to be a part of a lie anymore, and he doesn't seem to understand that. Now he barely speaks to me. He went from recently trying to hold my hand to ignoring me completely. I don't understand what the problem is. I told him my condition. It's not that difficult. Just tell her that we're friends, and everything will be fine! I don't know what to do! I miss him! He WAS my best friend! Ugh. I guess my question is too complicated to sum up in a few words...but I basically just want to know..What the heck is he thinking? Why is he asking me to stay in his life, yet when I try to be, he ignores me? Why does he think I don't care about him when HE'S the one who hurt ME? How did the tables turn that way? I don't understand! What can I do to make things better between us?