She's old enough for an honest talk about the disease of alcoholism. Not badmouthing your AH, but just to let her know that her dad has a disease and nothing going on is her fault or reflects on her in any way.
I grew up in an alcoholic home. That kind of honesty would have gone a long way in helping me understand why my mom left my dad and why he behaved the way he did.
At 11 she is old enough for Alateen meetings. Not sure if you are involved in Alanon at all, but those meetings have helped me a great deal, both in dealing with my ACA issues and in dealing with my ex.
As others have said, get important papers together, prepare to meet resistance from him. I made similar boundary- I will not live in a home with active alcoholism- and I ended up leaving my relationship because my ex was not ready for recovery. I had to act to protect myself and my children.
Big hugs to you. Stay strong and keep posting.