Having the chutzpah to apologize should be enough for everyone to let it pass.
I'm kind of worried about my reputation on this site to. I'm worried that when someone reads this, the next time they see my name they will assume the same thing will happen and just avoid me.
He was probably pointing out that if you are on 4chan you don't care about reputation. The last thing you care about is reputation if you are part of that site.
Then what did you mean by "fellow 4channer"? Everything online that I've found says a 4channer is a member of 4chan and that a lot of groups consider being called a 4channer to be insulting. Saying "fellow <whatever>" means you and them are part of that <whatever> thing (ie. fellow programmer).