It sounds like you're stuck in your thinking and should speak with a therapist. When we can't move on from something, it's important to ask ourselves: How does holding on to this benefit me? Your immediate response, most likely, would be that it doesn't benefit you at all and that you hate it. Yet, if you take the time to look deeper, you'll probably find the answer.
You may be holding on to punish your dad, thinking if you forgive him that it lets him off the hook. You may be holding on to avoid moving forward with your life and trying new things, feeling safer living in the familiar comfort of the past. You may be holding on instead of reconciling with your dad, being fearful that you could be hurt by him yet again. Only you know the truth to why you're clinging to this anger.
Whether you decide to remain estranged or reconcile, the goal is to find peace of mind, let go of the rage, and live in the present moment. Yet, as I said, you seem to be stuck and need some help getting unstuck. Albert Einstein said, “No problem can be solved from the same level of consciousness that created it.” That's why it would so helpful to talk with a professional who can provide new insight and get you to see things in a fresh way. A good cognitive therapist could accomplish this in a relatively short amount of time.
Life is precious and this has been going on far too long. The current way you're thinking about this situation isn't working so please get some help to change it.