I categorize my grudges and place them on different levels as someone would use shelves. Some I care about for 5-10 mins, some have popped in and out of my life over decades.
My last grudge was with a former employer 2.5 years ago whose idea of a HR department was an ivy league law school graduate who made her decisions by who smoked with her at lunchtime. No one could stand her, but all her smoking buddies got the promotions and increased responsibilities while the rest of us watched. She had the professionalism of a tabloid newspaper! She was a gossip and culturally ignorant--totally void of any diversity training (but remember, she was the HR director).
She is on my unique level of what I call "the fireman's club"-only a few "special" people wind up there. In other words, if she were on fire, I wouldn't piss on her to put her out!! Those special people become my fuel I use when I need to get to the next level. I think of them when I want to throw my hands up and quit. I think of them when they talked about me behind my back and made their stereotypical assumptions about me. No one thought I'd get my MBA, but I got that sucker kicking and screaming; most of the people in that office barely had bachelor degrees.
When people mistreat me, I get angry, hurt, sometimes depressed. But I don't stay there because I have a point to prove; first to myself, then to my naysayers. I always end up better than I did when I started and even if they never see my progress, I know I'm better. Success is always the best revenge to me...........