"So I've met this guy about 2 weeks and a half ago"
"even though I haven't met him face to face"
So either you haven't met him, or you spent each encounter back to back ?
"both of us got out of a relationship like one month and a half ago"
"he was with his ex for 10 months"
Oh next to no time there then.
"I was with my ex for 3 months only"
Hardly a proper relationship then, had a few dates and spend a little time together; didn't have time to get to know them that well.
"He still keeps in touch with his ex"
Well I don't think you have to have to break off a friendship if a closer relationship ends; but at this stage it isn't clear he has truly finished and one should take things slowly for now. Not expect too much.
"So I've met this guy about 2 weeks and a half ago, we are going to be classmates in the fall at university. He is really nice and sweet ..."
I take it that this is an accidental double paste and not a second guy.
As I said above; don't expect to much yet. Take it slowly, there's no rush. One can be friends and see how things go. If you don't start committing prematurely then you will be less hurt if it doesn't go anywhere after all. And if it does go somewhere then all the better.