I ghosted my best friend over 20 years ago. I still feel really guilty about the time he was trying to contact me.
Why did it make you feel guilty?
I feel like I owe him something because I ghosted him.
We all have times in our life and we want to cut contact with others, but it's good policy to explain to people why you're cutting contact or being distant. If you cut contact with someone without explanation then it's reasonable to feel guilty, because they're likely confused and upset. Even if it's been a long time, you should reach out and explain why you ghosted your friend.
He doesn't want to talk to me and I'm not going to try to explain myself.
I understand that you don't want to dredge up old memories, but leaving him alone without any understanding of what happened is wrong. If he doesn't want to talk then you could write him a letter, but you need to give an explanation.