That sounds very hard, and I can only imagine how much distress you’re in to be thinking of disruption.
I agree it’s well beyond a bit of a parenting class, what support do you currently have in place? Has he has/is having any therapy input, it’s not a magic wand, and things can get worse before they get better but it does give him space to process things.
Do you have a sense of what’s causing things to worsen, by that I mean are there learning difficulties, FASD, difficulties with his sense of identity, rejection of you as his parents? If you have an idea of what it might be about it’s easier to identify appropriate supports for him.
Do you and your husband have access to support for yourselves from other adoptive parents, through therapy or other groups? It’s easy to end up very isolated, thinking it’s your fault or that you’ve failed. This age is so very difficult for adopted children and their parents, for many varied reasons.
Do your SW services know you’re seriously considering disruption? What are they suggesting as an alternative?
While that may well be devastating for your son (and I’m sure you know this), it would be equally devastating for you and your husband to be physically harmed by him with the consequent impact on you both and him. One option may be to look at the possibility of residential care where you maintain the parental relationship but he gets the professional support he needs - I don’t know how possible that is and I’d expect your LA to push back because that kind of placement isn’t cheap but it might give enough space for you all.
Given his age, I’d be starting those very hard conversations sooner rather than later, because assessment processes can take a while once he reaches 16 it becomes more tricky because technically he could live in a supported accommodation/after care type placement rather than in the therapeutic type place he needs. They will try to kick the can down the road in the hope that he ages out of some services, so you’ll need to fight all over again.
I’m sorry you’re in this position - I know it will have taken courage to be so honest about being at your limit here, hopefully some of our long term/parents who are past the teen years will have some wisdom for you.