The only way he will ever change is if he seeks sobriety and is doing it for himself. You did not cause it, you cannot control it, you cannot cure it. You cannot motivate him to want sobriety. It may work for a few months or days, but not long term.
You have dealt with an alcoholic father, so you know what it brings. Do you really want that in your own life? He is not two people, the sober person and the drunk person are one in the same. Alcoholism is progressive, so that will show itself more and more.
Many hugs, I know it's hard.