How is it you are getting your mistakes thrown in your face? The person is chastising you or you yourself are reminded by something they say or do? In other words, is it your guilt talking to you or is this other person actually abusing you with the past? If it is your own guilt, that's one thing, but if the other person is constantly reminding you as in: "In 1974, you did this and I'm still mad about it!" You have the choice to walk away from that conversation and refuse to be drawn back in. Perfection shouldn't even come into the picture; none of us here is perfect.