Hiya, my son is in exactly the same position as you, except it’s the mum who’s the alcoholic and my grandson is only two years old. Social services have been involved but they are useless as their view is that the little boy has one sensible non-alcoholic parent.
My son has no idea what he will go home to each day, and like you he is trapped because he’s the sole earner and couldn’t manage as a single parent. I really wish she could see that she risks losing everything and I am now getting completely sick of her chaotic behaviour, and beginning to think by helping her out I am simply enabling her.