Future - I am sorry you are having to make such difficult decisions.
For what it is worth, my mom is an ACOA. My grandmother was bullied by my grandfather's family to stay with him, and "not put him out on the streets." She bent to their criticism, and was physically/emotionally beaten nearly everyday of her life because of it (until he left her...). My mother wishes every day that my grandmother would have left him way back when and gotten them out of that situation. As a young girl, of course she did not have a voice/say in the matter. My grandfather is long gone - passed as a result of the alcoholism and who knows what else. The point I am trying to make is I see how my mother will always carry that with her, and long for a childhood free of the terror of having an alcoholic father.
It is heartbreaking when children are involved. I have one of my own with my AH, and it makes me cry often thinking of the grim options I feel I have for him (Stay with AH/RAH or have him grow up without his biological father) and the potential repercussions of each. I also struggle with my own thoughts telling me I would be taking a son away from his father, which is a battle I will have to overcome. But, I have decided, that I will not allow my son to feel the pain, turmoil, trauma, etc of living with an AH or someone who is back and forth in addiction.
I support you, and again am sorry you are having to make this decision. I think you are doing the right thing for your child.