You actually answered your own question in your first post. What triggers you is "feeling powerless", and you do remember the experiences you had in your history where you were powerless when it came to how your father treated you.

That is what every single trigger and flashback I experience has in them. My being in a "powerless" position. These drunks can be triggering because when someone is drunk you never know how they will behave when you tell them to stop doing something. Some drunks can get extremely mean and act out like your father did with you when you were younger. Ironically, a lot of individuals that consume a lot of alcohol or become addicted to drugs begin using to escape their own feelings of "powerlessness" and often when someone finally does get sober it is discovered they actually suffer from ptsd. Actually this is something I learned this past year when I was interviewing potential therapists to help me with my own pstd challenge. Actually, one therapist I saw had specialized in working specifically with recovering alcoholics that also needed counseling for ptsd.

Your father was definitely not a healthy functioning parent with any capacity to nurture any child.

Do you still play the guitar?