His family are brutal. Passive aggressive narcissistic bullies so it's easy to see where he's learned his trade
My eldest has already said his life would be over if me and his dad divorced
Do you see the connection here? Every day you stay you are increasing the chance that your children grow up to be like their father. You are not helping your children by staying.
The process of getting away will be shit. The whole moving house, job, school thing will be bloody pain. The divorce process will be grim.
All that is temporary though. Afterwards you will be sitting in your lovely peaceful home, feeling relaxed and happy, which will improve your relationship with your children.
No-one will ever shine a torch in your eyes at night again, you will never have to see teh evil smirk over dinner again.
Eye on the prize heart. The sooner you get started on the shit part, the sooner you will be in your new happy life.
He's probably keeping you too exhausted to make the change. Recognise that and use it to find extra reserves in yourself to make the moves.
If I try to infer that he needs to change he rants and storms off.
Sounds like a good result to me. Gets him out of your face faster. Are you afraid of physical violence following if you refuse to take part?