He saw it. Everyone saw it. What's done is done, man. Move on. Do better. You don't need to apologize the rest of your life. Everyone on your back has done some stupid shit at 17 we wish we could take back.
Oh he was/is a well-known online MK and Injustice player, went by so many names it's crazy, KHAOTIC_ZOOM and EMPEROR_PSYCHO were probably his two tags that were best known in this community, he goes by TAPDarkness now.