Do you feel your DH is a risk to your son OP?
If you do then of course never leave them unsupervised together and make plans to leave him.
But if you don't and your DP is genuinely acting in a way that he feels best and not to cause intentional harm then you need to both find a middle ground here.
I'm a social worker in adults (specialise on safeguarding). So admittedly I only see the extreme cases but my social work role before was similar in adults.
It's manageable when they are young but once they hit puberty and become adult men it can be horrendous and sometimes fatal or near enough.
I've seen grown men in their thirties and forties absolutely batter their 75 year old parents. Broken arms, fractures, spinal injuries. All sorts.
You essentially have a toddler in a 6ft fully developed man's body towering over a 5.2ft middle aged woman.
So you and your husband need to look at as many techniques as possible for prevention.
Sometimes things do settle in terms of violence but often when puberty kicks in the violence ramps up.
You need as much support as possible to manage this now. Manage it as a team. You will need your husband's physical strength as your son gets older if he still has violent outbursts.
I understand many people's shock and horror on here reading your post. However I think it can be very difficult for people to comprehend the intense stress that parents go through with a severely autistic and violent child 24/7 with no respite. Being exhausted and sleep deprived, often stressed financially due to carer role, supervising essentially a toddler who cannot be left alone, whilst also being violently attacked daily. It's incredibly stressful and psrents at times can do things they wouldn't ever do if they were fully rested and parenting a neurotypical child.
I've known lovely, kind, gentle parents snap after being badly assaulted after a week of 5 hours sleep and locking their child in a room for several hours whilst the parents sob. I wouldn't then go into the home and remove the parent! They need support.
I am so sorry you and your family are going through this. You need to be kind to each other (him to you too). Your both navigating a difficult ship in high tides together.
Lastly.. your doing a great job x