This is a tough one. Good on you that you’re trying to work on your (very legitimate) anger.

When you say you don’t want to forgive, I think what you mean is you don’t want to say, “what you did was ok”. But perhaps in time you can come to a place that is a kind of forgiveness, that says: “I don’t know what strange conditions and twisted understanding caused you to do these things, and I don’t need to know. You were wrong. I hope in time you will learn, even if I don’t believe you will. I bear you no ill will. Our ties are nothing to me, you’re just another person who does ill in this world. It is nothing to me.”

Does that seem like a reasonable goal to aim for?

As for the anger itself, what helps me is to try not to rehearse the anger by thinking about how wrong they are or what I would say to them or why they are like that or venting about it to a friend or any of that kind of rah rah rah stuff, but instead just feel the anger, quietly, without mental narration. Focus on the physical sensations of being angry, until they fade, and keep extinguishing the thoughts that call up this angry feeling.

This is hard as hell for sure, and you have to make sure you don’t quell your anger out of a sense that it is wrong to be angry. You are right to be angry. It’s just not helpful to you or anyone else. Keep your eye on that more peaceful internal state that you’re after, and remember you’re doing this for you, it’s nothing to do with him. You don’t have to care about him, and you’ll hurt less the less you care.

It will take time. I hope you find your way.