I'm a mom too, with an alcoholic son. He's 27. He's a hopeless drunk like his father. He hates me too... and I've often felt like I failed him somehow. Truth is I didn't fail him. I was the parent that was there for him when he was a teen and heading for trouble. I held him accountable, and still do. I also cut off contact with him this last Fall, for the same reasons you expressed. (it was all too much for my heart to bear, watching him fall into the depths of alcoholism - and being effected by it in the same ways... emotionally, financially). I realized that there was nothing I did to cause it, and nothing I could do to change it. It's up to him, as it is your daughter too. But, boy it is hard to do, I know.
They blame us, because they don't want to take the blame.
You are doing the right thing, and hopefully both your daughter and my son will wake up soon and realize they need to change. I might add, when I made the decision to pull back I told him why, told him that he was an adult now, and in charge of his own life. I wished him happiness and told him that no matter what, I'd always love him as my son... but that I could not be witness to his life as it was.
Now, when I think of him, in a way it's like he's deceased. I think of him in past-tense... and remember what a wonderful little boy he was. That seems to still fill my heart with warmth. I hope you can bring forth some of those good past memories too.