Do what you have to do. I like to think of this as my motto in life. Sometimes in life when thing happen, we dwell on things that we could have done or should have done. We need to concentrate on what to do at this time in life. I always say, I did what I had to do. i found this quote by William Durant, founder of General Motors: Inspirational Quotes: Overcoming Failure "Forget past mistakes. Forget failures. Forget about everything except what you're going to do now - and do it".
Forget the past, don't worry about the could of, would of, should of, instead think about how to solve the issue at hand and do what you got to do, and do it now. And remember 'Life is what you make it', so don't just sit there, take action.