There is sound advice in this thread, especially from sir dooble, but let's not forget that this is a crush. There is a reason that it is called so. That is, if it isn't handle right, it will inevitably "crush" you. And honestly, there are only two sound ways of handling it.
One option is for you to drop any and all notion/hope of anything more ever happening between you two and just continue on your merry way. This isn't a bad way to go, especially if you're 90% sure or greater that he is not interested in you (that doesn't seem very likely, judging from this thread).
The second option is for you to approach him and tactfully explaining your feelings for him. You've known him for such a long time, so I'm sure you have some idea of what he is like on the insidegiggity. If you think he will accept you for who you are (i.e. being gay), then you should have no reason not to come out to him.
You don't even have to come right out and say that you're gay. I remember approaching one of my crushes and having the conversation go along these lines:
[insert friendly small talk here]
Me: "Hey, can I tell you a secret?"
Him: "Yeah, you know that you can trust me." [/smile]
Me: "I've been having feelings for guys lately... Have you ever felt that way?"
Him: "Yeah...? Why do you ask?" [/uncomfortable body language]
(At this point, I could have ignored the body language and told him I had a crush on him, but I decided to not make things weird.)
Me: "Oh, well, I think I'm gay."
Him: "Oh dude, I already knew that. lol"
Me: "Whaaaa...?!" [/surprise] "So, we're cool?"
Him: "Of course! Who is it that you are liking?"
Me: "Oh, that isn't important, lol. I just wanted to know if you're cool with me." [/smile]
I did eventually say that I'm gay, but I gave him a chance to tell me his position on that topic without explicitly coming out to him. I also read his body language to give me cools on whether he is having similar feelings for me.
Anyway, the point I'm trying to make is that, should you actually decide to approach him about this, you should take your time and not force any of your feelings on him. Let him open up to you so that you can freely express yourself, but just do that slowly. If at any point he seems uncomfortable, steer the conversation away as best as you can, because even the best of friends can be lost if things get too weird for them. It doesn't mean anyone is a bad friend, it just mean that they don't know how to handle the situation and would rather leave it alone.
In the meantime, do what others are saying and distract yourself from thoughts about him. If my guess is right, this is just an infatuation with him that you've been nurturing for for the past year (btw, this is extremely unhealthy, you're just going to hurt yourself that way). If it is just that, then distracting yourself will help you get over it safely and swiftly.
