Your husband sounds like a wise man. If she has money for booze, she has money to help herself. It will be hard to be polite about it. But simply tell her that and that if she focuses all of her money on helping herself and still can't make ends meet you will be there for her. But as long as she keeps up her drinking you are not financing her habit.
She will likely blow up at you trying to make you the bad guy. Just tell her your mind is made up and she can contact you when she is ready. Then walk away.
No guarantee she will come back to you if she needs you. But that is her choice. Don't feel bad if she makes bad choices. That is all her, you can't control her and you can't fix her.
I wish you luck however you decide to handle it.