Well, I've never turned down a direct request before.
You know that feeling you have for him? That's love. Or at least a variant of it. It's not attraction, or a crush. When it happens for the first time, people tend to be really confused by it. "Why do I like him? I like tall/muscular/blonde/smart/sexy guys, and this guy is short/fat/dark/dumb/geeky." But think about it. It's not just the tall, muscular, sexy guys getting laid, and partnering up. And thank God for that, because the rest of us need love and sex, too, damnit.
But as amazing as love is, it's sheer hell when you're in love with somebody who doesn't, or can't, love you back. Which is why there's all those "I'm in love with a straight guy" threads here, and they're so full of heartbreak, and they all have the "if only I could suck his dick just once..." bargains that never work out.
So what do you do? Honestly, I'd say go for broke. After all, you're not really friends anymore. If you piss him off, and he decides never to talk to you ever again, that just about puts you where you are right now. I don't get much "gay" vibe from him from what you've said, but again, you never know. I'm a sports nut, and I likey the dicky, so it's certainly possible.
I wouldn't contact him out of the clear blue and say "Hi I'm gay, hoping you are too, let's hook up". Perhaps send him a "catching up" email. In either that one, or the following one, let him know you're gay. You don't have to give him a long "I have something horrible to tell you" routine. Just say something like "I've made some good friends here at college, but haven't gotten anywhere dating. I was hoping I'd find some more gay guys here, but so far haven't had much luck. I may join the GLBTSU soon, and maybe that will help." Again, keep it conversational, like it's no big deal.
And that'll be his cue. If he chooses not to respond, there's your answer. If he responds, but doesn't say he's gay, you can take that to mean that he isn't. Do NOT force the issue. Don't cling to some scrap of hope that maybe he is, but he doesn't trust telling anyone, and and and. If you come out to him, that's his cue to come out to you if he's gay. If he doesn't take it, he's straight. Accept that, and move on.
If he does say he's gay? Well, then, have fun.
Lex