Why is my best guy friend actin like an A**??maybe u boys can help!?

My best guy friend and I got romantice for a short while and he told me a bunch of stuff about how he liked me and this and that only to dump me right after and say he only wanted to stay my friend... but then I got back with my ex who he doesn't like too much. And now whenever I talk about him or any problems that he and I (me and my ex) he says stupid stuff like "just go make up with that lil maggot" and "hope it works out...or not!" and one time I was talking about me and my ex and he was like hey check out this girl for me and he sent me a pic of a girl for me to tell him whether I thought she was hot or not... I was like ok yeah she's pretty. Then I'll ask him what he means and he'll just leave or stop talking. So I sent him a message asking why he does that stuff about me and my ex because now he makes me happy, but he only read it and won't answer!!! What's his problem?? why's he actin like this he left me!!!