I had told my X many times, even right before I kicked him out, that I wanted a divorce, that it was not working. It was always, "I will work on things, I will get better, I will prove it to you." And he never would. So, I kicked him out and let him know that I plan to move ahead with the divorce. I told him I will always care for him, that I want to successfully coparent with him, but that this was not working as a married couple.
He could not believe it. Even though I had said it over and over, he still was in awe that I would divorce him. And angry, and sad. He still has not gotten over it honestly, and he is remarried!
I hope detox is not all she is doing. I hope that she is somewhere that a counselor is available, and that is when I would tell her. Tell her so that she is in a safe place to go through those emotions.