Wanting to get revenge on an ex brings out the worst in people, because it's very, very personal. You slept with the person, lived with them, shared all of your worst secrets and deepest dreams with them. So when you feel betrayed, it pretty much destroys your faith in humanity and any hopes for future happiness.
The key is to try and keep your enthusiasm for life by doing things you love and going after what you know you need to do as an individual to be happy. And sometimes that means getting violent in the right direction, whether it's going hard in the gym, kicking ass at work, or finally taking up that hobby and going at it with full force so you can finally get close to mastering something in your life.
Getting violent in the wrong direction is always, a bad, bad idea. Like don't elaborately plan the death of your ex. And don't go and set their car on fire.