Tu Quoque Fallacies.

Has there ever been a time when you were guilty of the fallacy of Tu Quoque? Basically that is (If you have ever said, “Yes, I did X but she did Y first,” then you have committed a Tu Quoque fallacy.) Honestly speaking did you think that justifying your behavior based on the behavior of someone else legitimized your own behavior in some way.
Please explain whether you think that you will respond in the same way if a similar challenge is raised again. Please help with any insightful responses to the question, as I am curious to know what others think.

I make the decisions for what I do in my life and either enjoy or suffer the consequences of what I decide based on how clearly I understood what I was deciding. Catchy phrases aside, it really is that simple.