I find joy in watching negative things happen to the people who treated me badly in the past
Is it the revenge that makes you feel so good about it?
They should be punished for making me feel miserable
Being treated so badly in the past can make a person bitter. Use that happiness you feel about their demise to help them instead, it will make you feel better in the long run. You can go to bed with a totally clear conscience.
Fuck helping them. They don't deserve it.
They may not deserve your help, but lingering on about them and wishing them ill-will isn't healthy for you. Don't let the bitterness of revenge control your life.