Dude, delete it and try to forget, nobody is buying your excuse. You called someone dumb for making a mistake, despite it being you who made the error while OP was bang right.

It's very embarrassing mate, you can try to style it out all you want and a couple 10 yr olds might buy it but not much more than that.

Personally I think you'd do best deleting the comment and trying to forget that you were just that stupid once upon a time :) x