Revenge Therapy

Revenge Therapy is the act of coping with your problems in life by being cruel to others
Usually, the cruelty will be directed at those that bear similar qualities, usually physical, to one's oppressors

"Ever since Markus got harassed by that one racist guy he's been unusually cruel to me, what's up with that?"
"Oh, he's coping with revenge therapy. It's probably because you're white."