I have wondered what I would say to my XABF's mother if she contacted me about her "special boy."
It's like a weird game of volleyball and they keeping thinking that spiking his alcoholic behind back over the net at you is going to take away their baggage somehow.
I've always thought, "Well my dear, you raised him, I kept him clothed, fed, and financed for a while, you should have changed your number because now he's back in your court."
I think you handled yourself as best as you could considering the enormous triggering of emotion that call must have caused. I agree that if he prompted her to call you, he's got some serious maturity issues going on. If he didn't then she is a serious meddler who probably feels enormous guilt watching her little wonder suffer his own consequences. If he's working a program then he has the tools to manage his feelings and to keep his recovery out of his mom's business.
Take a deep breath. Walk away from the phone. Let the two of them hash our their own issues. That's what sober adults do, right?
Best wishes!
Alice