The past is the past is the past...

"The most obvious thing about which you can do nothing now is your past behavior. Everything that you ever did is simply over, and while you can almost always learn from it, and sometimes change effects that are continuing into the present, you cannot undo what you have done. Therefore, any time you find yourself quarrelling about how you should or shouldn't have done something, instead of discussing how you can grow from your past errors or what can be done now, you are a victim in a no escape pitfall." (Dr. Wayne Dyer. 1978. Pulling Your Own Strings. Chpt 3)