Think about how you hurt his feelings and recount the situation and tell him how you were wrong.
they are basically being a douchebag
Tell the person you are truly sorry for what you did and want to make it up to...
Try flowers,or a card, that's always nice.
Never ruin an apology with an excuse. An apology is a good way to have the last...
Just be honest to why you are sorry. That will go over then rewritten lines.