My ex making me feel guilty.

Ok. So here's the deal. I just recently broke up with my boyfriend of almost a year because I realized that he treated me great when we're alone but treated me like crap in front of his friends to be cool. He was mean to me and my friends and even one of his friends! Overall I believe that he is a fantastic person but just wants to hide it to be cool. So I'm asking for your advice. I am positivley not getting back together with him but I feel like I left him without an explanation. I just said, I don't think we should be dating anymore and he said "sick". I ran to the bathroom and gathered myself. Yesterday was our one year too. He puts notes in my locker saying "I hope you'll forgive me. Te amo." And he's making me feel guilty. At break today he said "I don't like baseball." And I said "Why don't you like baseball?" And he's like "I don't know, why don't u like me?". I have to see him everyday and it's not helping me get over him. He flirts with the girl I've always been jealous of. I asked his best friend (also one of my best friends) if my ex still liked me and he said no. That really stung. He said my ex is done with me. What should I do? He's making me feel guilty. Should I give him an explanation? Just what should I do.