The anger you’re feeling is totally normal, totally human, and totally justifiable. What you witnessed was “Beyond”, and anger is a perfect emotion for having to experience or see the Unnatural, or Evil. The emotion of Anger is great because the alternative emotions are Despair, Guilt, Apathy, etc.

It is so OK to smash kitchen utensils (safely) into the ground, box a pillow, box the air, growl, “I will DESTROY you!” to the phantom of your father. Hell, light a Justice Candle. Petition the God(s).

Hiding behind the anger though is the grief of losing your father while he is still alive. That you deal with a therapist. Honor your experience and yourself by the gift of a good one.