OP,
Please ring Women's aid for advice.
Your children are in a highly abusive home, of that have no doubt.
I think asking the abusive parent to leave is reasonable.
I think you should expect him to get very angry and abusive when he feels his control slipping.
He is a bully, just like his father.
Calling the police on 101 and telling them your intention to end an abusive relationship because your husband is abusing your child, would be wise.
They can put a marker on your address and your phone number, should you need to call.
If he kicks off, please call the police.
He is a house terrorist.
The damage to BOTH your children is huge.
Please believe this.
He knows well that his behaviour is wrong but chooses to be a bully.
Does he behave like this in work?
With neighbours?
Family?
No, he does it to a 9 year old boy that is terrified and traumatised and now has behavioural difficulty.
You sound like a lovely woman who has made bad choices over the years.
Your children desperately need saving.
Please tip the police off.
Your eldest is unlikely to want to spend a lot of time with him.
Go to your GP and log the abuse and trauma.
Your children desperately need you to stand tall and call his abuse out once and for all.
Wishing you strength and resolve.