I also could have written your message. Only it was my mother.
She still is an alcoholic, although she claims she only drinks one bottle on a night. But, nevermind.
I have also been in your position, many times.
Like you, sometimes when dm is sober, i look and thonk ahh shes not that bad, why do i get so upset. Then i see when shes drunk and think why do i bother with her when she is sober.
I found that I, myself was the one keeping the family together.
How thay had happened, i dont know.
I think it was down to the fact my dm treat me so bad as a child, i was forver trying to prove my worth. I was the peacekeeper whenever my older sisters had a humdinger with her.
I felt like i was losing the plot not sl long ago. The pressure of my EA ex partner constantly reminding me how bad my childhood was.
I wrote letters, i confronted, i blocked off all contact. Not just with dm. With my whole family.
I guess thats what my ex partners plan was. But regardless of him, my problems around that issue were still there.
My point is, when i broke contact i thought it may kick start some action.
My mother became a recluse. My sisters no longer bother with her. They phone and speak to her at times - but they phone to speak to my dad...just talk tk her during passing the phone.
My dm never spoke to people. My dad claimed she had cut her drinking right down.
It didnt change the way she was with me though. Nor was she intending on changing.
I am back in their life now.
I have learnt to just try and get on with it.
Not knkw her at all with drink in her system and tolerate her when she is sober.
She is and always will be a bitter, cold hearted woman. At least i can say to myself that i have tried to help her on every single level. She just isnt willing to help herself.
Sorry, dont know if any of that may help you. But i hope at least it lets you see you arent alone