I would tell them that he is facing some issues in his life that are most likely difficult to admit to himself, so that is why it's difficult for him to utilize the help they offered via a psychologist. I would explain that denial is a very powerful thing and that he seems to be experiencing some of that now. That while you appreciate how much they care for him and your family that only he can reach out for help.
They will put two and two together eventually I would guess. More importantly, as they said, it looks like he may not have this job much longer.
So what financial protections do you have for you and your child should he lose his job or go down further into the rabbit hole with this? I don't mean to be callous about it. However, everyone who has a close relationship with an A should have protections put in place for their own future.
Hugs. I encourage you to keep a close support network for you! Take care!