The Epictetus quote for today provides some insight for handling this problem:
“‘My brother ought not to have treated me so.’ Very true; but he must see to that. However he treats me, I am to act rightly with regard to him; for the one is my own concern, the other is not; the one cannot be restrained, the other may.” - Discourses 3.10.19 [Higginson Trans.]
It's far too easy to use other people's shortcomings to justify our bad actions in response. It feels good in the short term, but in the end we race to the bottom, responding to bad treatement in kind, until we become just like the person who initially wronged us.
Far better to take Marcus Aurelius' advice: "The best revenge is not to be like that."
...not Spike Lee...