People who have recovered: How did you stop hating them?

Even though we have broken up. The rage towards them is eating me up to now. I spend too much of my energy in trying to figure things out and fighting him in my head. I m exhausted..

It's over but I can't stop hating him . It's been almost a year and I wish everyday that they get their karma.

It's taking too much of my energy. I want to be indifferent towards him.

Can someone tell me some suggestions..