I'm so sorry for your loss and completely empathise for how you are feeling. What this reminds me of is when my aunt passed who was like my mother to me just a year ago she had a long battle with alzheimers . Long story short my family are all the fallout of my father's alcoholism and I do not speak with him. But after she died I went through all the feelings you are having. I felt the guilt of we should of done more, I should have been there when I noticed the signs of her getting the disease, I should of moved in with her... I was angry we didn't get to spend more time together because I was so emotionally unavailable cause of the alcoholic in our family. I was angry at everyone else too because how they weren't helping etc and showing proper respect to her. I'd wake up crying in the middle of the night. Grief is all consuming and all your thoughts and emotions are so so so normal and valid but you did your best with what you had at the time emotionally and mentally. These feelings of anger guilt and sadness never really go fully away but it gets easier to live with. Sometimes we romanticise memories and think we could of done more etc but really you couldn't emotionally and mentally and thats not your fault that's how alcoholism impacts a family. He wouldn't want u to carry this as he loved you and im sure felt guilty as it was when getting sober. You should be so proud that he did get sober and you even had that small time cause some of us don't and won't ever get that. Give yourself time and let yourself feel, grief is a hard process but u will get through i promise and you won't always feel like this.