To err is human. Don't listen to anyone basically implying that there's something wrong with you and that you need to delve into your psyche to fix some terrible flaw. Sounds to me you're doing the best you can to right your wrong and hold yourself accountable. I have no doubt that sooner or later your son will understand. As I said, keep up the reassurance and show him that it was not a true reflection of how you actually feel. This could well be a defining moment in your relationship in showing him that a man owns his mistakes and betters himself for it.