I’m sad and angry. What can I do?

My father died just 10 days ago from cirrhosis. He had hepatic encephalopathy and all of his organs failed quickly. For 3 months, from when he first went into the hospital I took over his bill paying and also the mess of dealing with my grandmother’s care. My father was her POA and the only one. He stopped paying any of his bills or hers when he went into the hospital in early January. It was extremely stressful to deal with his mistrustful brother and to try to figure out a solution to that problem. I regret that it took up a lot of the little time we had left. I live in another state, am an only child. My parents are divorced and my dad lived alone. He never went home after being hospitalized in early January. I keep replaying how I might have done things differently. I wish he could have regained some strength, enough to go home. But, he got weak and ended up not being able to walk. The lactulose made him live in adult diapers-he couldn’t toilet or bathe himself. Covid restrictions meant I only got to see him once in person in March. When I got the call that he was failing I left immediately and spent 3 days with him while he slipped away. It was terrible. I can’t talk about it with people in my life but I also can’t not talk about it. It’s eating me up.
I’ve busied myself with having to settle his affairs; I carried out his wishes to be cremated, I have to clear his house and sell it, sell his truck. But I’m left with this terrible burden of grief. He destroyed himself-why?? Going through his papers I found a letter I wrote him 15 yrs ago begging him to stop drinking. I offered to help him find a rehab place. It didn’t help. I’m so sad. I’m sleeping too much, no desire to work. I don’t know what to do.