I'd go against the flow here and say don't bother with trying to tell him.
I listened to all the advice, you know, you regret the things you don't do more than those you do, tell him so at least you know blah blah. It's all rubbish, don't listen.
The truth is if you know him and has been interacting with him he will have got some clues that you like him. And the fact he hasn't responded means he's trying not to notice because he doesn't feel the same, but doesn't want to lose your friendship. Tbh if someone liked you something would have happened by now.
So what happens if you track this guy down and confess all? he will um and ah and say things like, but I do like you, it's not that, it's just I'm confused etc etc. I can almost guarantee you won't get a straight answer out of him. And despite what you think is an apocalyptic bringing up of an unspoken topic that will forever change everything, it will change nothing. You still don't know exactly what he feels, you'll never get a straight 'yes' or 'no' and if you stay around you may have that conversation again and again, with the same inconclusive result.
So all in all you end up giving your heart away, without any kind of answer and without knowing for sure and being constantly in pain for as long as this goes on. All I can recommend, and this is some honest advice from bitter personal experience, is to not touch this guy with a barge pole! Cut off contact and just have him out of your life.