This might not help, but perhaps offer some perspective.
My dad was an alcoholic, or perhaps a dry drunk for my youth. I was born when he was 70 and he had been struggling with alcohol all his life, if you listened to his stories. He was an jerk and very damaging to his children. But. . . aside from our issues we turned out to be honorable and stable citizens.
But I adopted a little girl, my great niece, who was a drug baby. I don't know all the drugs involved, but stuff like Meth, Ecstasy, pot, alcohol. We basically knew she was going to have issues. At 6 months she showed signs of "shutting down" when there was too much noise or strangers. Some early evaluations suggested she might be autistic.
So we got her into some modern therapy, floor play, and an awesome therapist and she snapped back. She is 8 now but has been in therapy since she was 6 months. But she is great, aside from struggling some mild OCD stuff like germs and fear of the dark. But she excels at most stuff like singing, art, social skills, computers, schools, and stuff. Yeah, yeah, I'm bragging a little.
My point is, I've learn that alcoholism and autism and bipolar, and stuff, are all sort of related to the same disorder. Here your son is (how did you put it?) very, very difficult. Well, your drunk husband is being very, very difficult too. But for almost the same reasons.
In a way, your husband doesn't have much more choice in this than your son does. The brain isn't processing feedback from the world. Many autistic children start out OK but shut down a little later on around 4-8. Though the details different a little, the reasons are basically the same as what makes an alcoholic. They cannot process all the information coming in to them.
In the case of my daughter, it is more sensory related. So when she was young, every couple of hours we would brush her skin, arms and legs, with a special brush, do joint compressions, etc. Now, when she get "unregulated" I pull her aside and we toss a ball back-n-forth for 10 minutes. She right as rain.
She hates the attention to her issues but she is more aware of what she needs to do. So she will ask me to toss the ball when she needs it. But her sense of justice is on a god-level. Nobody can get away with anything.
But even so, she can get stuck in events. It took us a while to figure it out how to help her process it. But say someone hit her in school, or some kid threw up on the rug. It could take months for her to stop talking about it.
Autism is strongly about the mind not processing information and getting stuck in "obsessive loops." So are many mental disorders. But so is alcoholism.
Way more of us humans have these "quirks" then we might first suspect. We just don't catch them, but instead put people in jail that do stupid things. A study recently revealed that almost 70% of homeless people, and people in half-way houses are on the autism scale. They cannot keep jobs, they cannot focus for long, and they freak out under pressure.
AA works for alcoholics because it provides them a method of processing their emotions. The 12 steps are a diagram of how to work through denial and mental feedback that they have done something wrong.
So even if a person isn't "drinking" they can still have this mental glitch that inhabits normal processing of emotional data, causing build up that causes obsessions, distractions, and such that alcohol gives them a release from. And it doesn't all have be about bad stuff.
Humans can be happy. We want to be joyful and celebrate. But our culture is pretty uptight and so the only way to really let go and let loose is lower the inhibitions with alcohol. Even that "joyful" emotion gets blocked and causes disease.
I won't tell you what to do with your husband, but I'm going to suggest that your child has the same struggle, just earlier in the game and perhaps a little more serious.