Seeing this guy with another girl makes me so jealous, please please help?

[DropOfScye]

I've only been at uni for under three weeks, but I kind of got a crush on this guy there. Initially, he was quite withdrawn but then spoke to me a lot and I was the only one he added as a friend on Facebook. So I thought maybe he singled me out because ... well, I don't really know. Anyway, today I tried to talk to him, but he replied very curtly and then spent all the lectures hanging out with this group of others (girls). And then I saw on Facebook that he'd added this annoying girl as a friend.

OK, I get it, I should forget about any chances I might have. But how do I stop feeling jealous? It's still early, I'm obviously not madly in love with him, so there's hope I can nip this in the bud and make myself stop liking him. But how? Please please help, I feel quite sick even now. After I saw he'd made friends with her on FB I lost my appetite and all I want now is a cigarette instead of food :/

[?]

yeah... same things happens to me too. It's always like that. When someone is getting close, some b*tch take it away.. so typical. I really don't know what to do because i lost everything on them but it feels like you have to play. Girls nowdays are nothing but a thief. They use internet to steal everything even gay guys. You have to be very discreet or just be assertive. I think the battle get tougher and tougher.

[Mike]

Your going too quick too fast.

Treat it as though he's not hanging out with anyone else and see how your rel w/ him goes.
If you dislike his taste in other people than you really don't like him, seems as if it might be only physical. Jealously is normal, getting sick from it is not. I'd also tell you to stop smoking so much.
You can't let people get to you so quickly. You need to gauge situations better or let it roll off your back.