Welcome to this forum. There are many here that are and have had to deal with many of these same issues. We all have an alcoholic in our lives that we love but have had to learn how to let go of. She is not ready to help herself....as she is in deep denial. The only thing that you can possibly do is help those children.
I had a similar situation is that my oldest daughter was involved with an addict and they have a young daughter, my granddaughter. I also have a daughter, 10, at home. My oldest daughter has now left "him" and is staying with family here, but while she was with him she/they was neglectful parents. He did his drugs and whatever else and she would just zone out....space out and not take care of business. It was not a good scene for the kid, but like all things it had to come to a head eventually. I had already tried the talks and many other things to get her to come to her senses, finally I had to let go of it and let nature takes it's course. I did not allow my 10 yr. old to go to her sister's house while she was with him as I couldn't trust him not to harm her or give her drugs to try.
If at all prossible..take action for those kids sooner that later, but if you hit a wall, then it will be time for you to let go and let the consequences fall were they may, until there is an opening for you to try again. It's hard I know.
prayers for you and your family.....and special ones for those kids