I think this is true of me, and I know at least one other mother who felt the same way.
I agree with your husband. I believe that your absolute priority right now is to protect yourself.
I know this is supposed to be about your son, and his recovery. I believe his recovery is supported by your having boundaries and not allowing him to define you.
If I said anything at all it might be something like this, a general statement: I have taken responsibility for things SON says to me that are hurtful...as if I am at fault or did something wrong...when I know I did not.
I do not think I would say more. This is about him. Not you.