I’m in my 50’s. Both my parents passed this year. I didn’t go to either funeral. I felt nothing but anger at them. I did finally start going to therapy. My parents were different in their abuse but the same in that they never once in my life apologizes for any wrong they committed. It was physical abuse until I became physically stronger. Then it was nothing but mental abuse for the rest of my life. Admitting it hurts and admitting that its the source of your anger is good for you.
My parents like many didn’t “believe” in therapy. For good reason as it turns out. They knew they are guilty of abuse and feared exposure. Give it at least a couple of tries. If you don’t like the therapist you see. See another one. Be prepared to hear things you will not like. Acknowledge your pain is driving negative emotions and keep trying to not let it rule you.