What do you think is the deal with this guy? I need your opinions?

[nic.ber]

I had a friend who i stopped talking to last year but about 6 months ago she started talking to me again.
Her boyfriend caused us to no longer be friends anymore. Last year on my 17th birthday right before i went out he emailed me and said some hurtful things.
About 3 months ago he emailed me again apologizing saying he was in the wrong that he shouldn't have said those things to me especially on my birthday, but he said i deserved it.
He constantly talks bad about me still to his friends but when he talks to me he acts nice.
On his twitter he'll post updates that are mean and they're directed at me. But then if i post an update he'll talk nice to me.

i don't know what his deal is and i don't know what to do.
what do you guys think?

Also I'm 18 and he's 20 it's not much of an age difference but I think i act more like an adult than him.