I agree. Why live with regrets that will haunt you? You may as well find out for sure and put your mind at ease, regardless of what happens.
Go to his door -- and just plain apologize. Yes, I know it's hard to apologize, and it takes a big person to do it, but BE a big person and DO it.

You'll feel much better about it, and so will he even if he's moved on. He'll feel better about you too.
And you never know -- maybe he hasn't moved on. You might get back together. All it takes it a knock on the door. Best of luck & God bless. Hugs, Lee