You need to access more support, your local authority should have a list of support services for for SEN. In my area there's an autism charity that provides training in dealing with challenging behaviour, including how to deal with violence. You need this sort of specialist support. It is out there but you have to look for it and in many cases pay, you can't rely on social services or GP.
This is how I have used zones of regulation, which has really helped me, although my situation is not as difficult as yours sounds, so I appreciate this may not be appropriate for you.
I gave my DS a small card split into 4 with the 4 colours on, and in each I wrote two emotions. I explained what the card was. Then when he was in an ok mood I asked him "what colour are you?" And at first I had to prompt e.g. you are smiling so I think green. So he learnt what the colours meant.
Now when he starts to get angry I say: ok I can see you are yellow, how can we get back to green?
Sometimes he loses it and is smashing walls, doors etc and I say ok I can see you are red, you are feeling bad, and I try and talk him down back to green. This is so much more effective than the way I used to respond because it removes the blame - it's like I am saying ok you are in a bad place how can we resolve it, rather than saying DS you are bad.
This method has really helped my DS to recognise when he is getting angry and to take steps to calm down before he loses it. It's also helped him to realise that when he loses it he does things that he feels bad about later.