I'm going to be a big ol' Debbie Downer here and say "Talk is cheap". The grand gestures of throwing away booze and ciggies may be impressive, but if she wants to get herself well, SHE will take action, daily, to make it happen. It's a lifelong struggle. Also, the fact that she asked you to call irks me. It makes me wonder why she didn't do it herself.
If there wasn't a child involved here, a nursing INFANT, I would still say to be wary of the situation, and to keep focusing on your own recovery because you might end up being disappointed by her grand gestures and statements. But since there IS a nursing infant involved, it seems to be it's your responsibility to ensure that your AW is not left alone with her child because of the potential danger she poses him. The suggestion of a mother's helper is excellent. A lot of new moms make use of that same service simply to give themselves a break. Have you been able to talk about all this with her doctor? A social worker? You need some support to see you through this jayscott.
Keep us posted, please!