Please help

So a bit of an overview. Me and mum have been together 8 years and have a beautiful 7 year old daughter. I have a 10 year old son with a previous partner who I'm not allowed to see, I pay a maintenance weekly but he has severe autism and ADHD. Contact was fine until I met my current partner but by the time I got to a solicitor (I thought the anger would wear off) I was told ig would be an uphill struggle including Contact centres and I didn't want to put him through it. He will never live alone and hopefully someday things will shift a bit. So my current partner has a son, I'm white there both mixed race if this is at all relevant. Our daughter is feisty, outgoing and brilliant everything I could ever want. 6 months after she was born me and her mum went out for a night for the first time, lots of resentment was let out and the night ended with an argument. I'm a fairly hefty guy (soft as *****) and eventually I said right were going home, mum was sat crying emotionally on a bench so I grabbed her arm to take her to a taxi. At this point 3 squaddies came over and got involved I ended up in an altercation I thoroughly lost got a split lip black eye etc and arrested. I was charged with assault on my partner which was laughable but the UK police can do this within authorisation from a (victim). Hired a solicitor was assured it was an easy case to win turned up at court to be told if I didn't plead guilty then they would charge me with assault against the 3 soldiers who battered me. So I have a police record of domestic violence. Now my 🚶‍♂️ has never been the easiest he's 12 now I've been there since he was 3, dad's a ***** in and out of prison but nervous enough of me not to play about hasn't seen him for 5 years. 99 percent of the time stepson is great, very quiet but ok. He has flip out moments but he will scream and shout that I'm hitting him when I'm not touching him. Yesterday he done this at my work. I'm a licensee and run pubs, if I was arrested for child abuse (with my dv record they wouldn't think twice) I would lose my job, home career access to my other children and tbh my will to live. Mum doe's think it's a big deal but I'm raging. She agree he needs punished but what🤷‍♂️🤷‍♂️ has to be serious. No devices doesn't bother him, early bed ti.e won't work. He's 12 how can I get him to learn consequences for his actions