It's ok to make mistakes. The question is, is it really a "mistake", or something else? A mistake is an accident. Maybe what you are referring to is not an accident, but more something you did that you knew was wrong, but could not talk yourself out of. Something you really needed to do at the time, but later wanted to undo. That is not a mistake, but an excercise in poor judgement. What you need to address is the reason it was done, not the act itself. Figure out what needs to happen for you to have no reason to make any more of these "mistakes". Then you will need no line drawn at all!