Sounds as if you have a fairly good education surrounding addiction and neurophysiology . . . this forum has much good information in the stickies under classical reading. Often recommended is Melody Beattie's Codependent No More; I also have found Byron Katie's books helpful (Loving What Is, but all her books are good).
Support groups are actually very helpful, but I'd be approaching that one at his facility with caution. Anonymity is important so that you can express what you need to express, and you just don't know what family members will repeat to their qualifiers in treatment with your qualifier.
That being said, there are many in - person and zoom AlAnon meetings, and you might find AlAnon really helpful ( and this is for you and your benefit, not your qualifier's).