Grudge or Glitch?

Why do we as human minds hold on to everything? I don't care if you dis agree because your lying. Everyone does it just some people hold on to it tighter than others. It's this Constance battle in my head I don't want to feel hate and negative thoughts. But I have let them invade my life and I can't find out how to get them to go away. Sometimes I feel as if violence is the only way and I just want to beat it out of myself. By hurting the people I am mad at. Underneath it all I know that it would only hurt the situation and, make things more complicated. I feel as if  I have this permanent glitch in my head that keeps going right back to negative thoughts. So is there some sort of wiring in my head that hooked up wrong? Or is it just me holding on to hatred. Only god knows, I hope one day I can train my mind to just let stuff go. Until then I ask you this, If they legalized murder for a day who would you kill?