He may have more of his father in him than you would care to believe.

Sorry you have this heartbreak to live with. A letter written on paper and sent via snail mail may have more impact than the emails have had. You could just say that you are sorry and leaving the door open, in case he changes his mind.

He may feel that you've never really taken responsibility. Abused kids don't want to hear, "I did the best I knew how." When you think about it, that's granting yourself a kind of absolution. Neither can you accept a relationship that requires you to beat up yourself for ever. People do make horrible mistakes. Your advisers may be right about how you can't live forever in the past.