Did you attend his funeral? If so, did it impact you emotionally, or did you attend super dissociated? Writing can be helpful....as can writing down each thing you wish you had said to him on separate pieces of paper, and telling him what you thought, after he was dead and burried. I did that and found that helpful....and I'd toss each one in the fire pit after I said it aloud and tried to mentally "let it go"..... It is also equally powerful to have one other person there to witness and I selected someone who would understand and go along with my faux funeral, but getting it out verbally and emotionally....and then saying "Goodbye"......parting ways, separating the past from the present, and closing that door because he is no more.....he can't hurt you anymore......you are safe. That process was super helpful.
I'm sorry you have such painful memories of him. When I did this....I felt a sense of relief after saying everything I had to say..........I was better able to let go...and I didn't do it in a ugly dispicable way, I just said my peace and kept my dignity. It was like watching the final episode to the show, My Father and I.........and I allowed myself to spend the next day in bed sleeping (it helped=planned down time), in seclusion.....with things that were comforting in my bed......because there was a lot of grief....not much grief for his death....but plenty for the losses and pain caused by him....and the loss of so many possibilities for myself. So I strategically did this on a Friday, in my back yard, so I'd have all weekend to recuperate for the following week. Saying goodbye, breaking that tie to the past, was a critical step towards healing for me. Good luck, there.