Help with a guy? Get over him or ask him what he's doing?

Basically i got with this guy on like 3 occasions. In person he is perfect, but on msn he is so different. He's weird and mean but in a kinda jokey way, but i just dont know how to interpret him when he's on msn. Things were going fine between us, we were meeting up, getting relay close and it was like we were besties. The day after i got with him the 3rd time, i found out he had been bitching about me to some girls in my year, saying i was a slag and he'd never get with me and that he'd ditch me for them any day. I was really surprised but i didn't do anything. Then today my mate asked him to apologise to me and he said no and completely ignored me. Later on today, on msn, he said to me 'what is your mates msn, who was talking to me?' and i said idk and he said 'well you should, nice one, this is why i dont like you.'

i dont know why he wanted to talk to her, but it probs wasn't about me.

What is he doing? I got no apology for him talking about me behind my back, and he is rude to me, when i'm the one who is meant to be all p*ssed off with him. What is he doing?! (And btw, he deffo was talking about me, and he knows i know.) PLEASE%26amp;%26amp;THANKYOU xxHelp with a guy? Get over him or ask him what he's doing?
He's an asshole. Forget him Im sure there are better fellas out there for ya then this tool