"the thing with adhd or any other diagnosis people want to put on it (including 'anger management' problems) is that these things happen in more than one location and with with more than one set of people. whereas domestic violence and abuse does not, it is contained, controlled and exerted only where it is safe for the abuser to do it."
This doesn't always apply, and I believe that because ^ this is the generalised view, it is nigh on impossible to get appropriate understanding and support in cases like this, which leaves too many parents alone and helpless when dealing with difficult behaviour.
There is a book called The Explosive Child which would be worth looking at, it may be aimed a little younger than 14, but has strategies that would still help.
My 9 year old is very like this. On the ASD spectrum but not enough for a diagnosis, but our day to day lives sound similar to yours, yet he masks it in school and other places, so when we try to get support, we gat blank looks and unhelpful "but he's fine". We are trying desperately to get on top of the situation, or I fear greatly for his future.
From your posts it doesn't look like a case of you letting him walk all over you, and I do understand that for people who don't have dc like this it's very hard to understand, and it's not as easy as getting your Dh to get really cross, or knocking this on the head - if you could! You would. I think you've all got to a very low point, and understandably you don't know which way to turn.
I also understand that it feels like a huge disloyalty to even consider ringing the police, but this may be a way to get some help.
Wanting control can often be a manifestation of anxiety, even though it looks like out and out violence for no reason.
Is there any chance you can take a bit of a step back to see if you can spot triggers? Eg. Theme parks could be a change in routine, crowds, something like that which may be completely off your radar. Controlling what everyone does could be his way of coping with that.
I don't know who to recommend you to go to, because we're still in the same boat with ds, with no-one who will think outside the Crap Parenting box, even though we have other dc with no violent tendencies at all.
If there has been an assessment in the offing, I would push again for it, but also maybe consider ASD or PDA as well.
Even if you don't get a diagnosis, knowing vaguely what you're dealing with will help you to understand how to deal with it.
Good luck, I hope things improve for you 