It's called Revenge with a capital R. Because the notion of getting revenge has pierced the walls of your personality where it now becomes a part of who you are. It's a persona because it latches on and superimposes itself.

You have to make now a heroic effort to get yourself free from its clutches. The area of free-will has been taken over in that part of your heart and soul that discerns between right and wrong. Morally (intrinsically and logically) you know this to be wrong, but you choose to do it ANYWAY. That ANYWAY is the Revenge talking and doing. It then will sit in your heart eating away with GUILT. And the road downhill is a surefired one.