Mistakes happen, plain and simple. True individual not only learns from the mistake but is able to fix mistakes without creating set backs.
I make my share of mistakes and live up to them. I don’t cast blame to others and I do not dwell on wrong doings by me or others. Pretty much examine the situation and move on. I can say for sure I never made a mistake that I did not learn from. Usually I somehow incorporate my mistakes into future learnings for others.
The only mistake that I could consider unacceptable is to not live up to your wrong doing and try to pass blame or hide the mistake hoping that it will never be seen. surprisingly this is the easy route that some people choose to take. Once this route is taken though it is hard to live a positive life style and short cuts and bad habits become a way of life.
Live up to it, for you only live once and a negative life in my opinion is not one worth living.