I had a friend who i used to work with, her partner used to beat her.
At first he'd do it to her legs and body, but eventually he started on her face and head.
I always remember the day she took me to the toilets and showed me what he'd done to her.
I was in tears and physically sick at seeing her injuries.
She used to say it was HER fault that he did it.
Would make excuses for him constantly.
He'd come back after being arrested time and time again and say he'd change!!!!
Change for a few days or maybe a couple of weeks.
Don't take him back like she did, a leopard will never change their spots!!!!!
Speak to the school teacher or headmaster a.s.a.p. they will probably be very sympathetic to you.
Tell the children that although mummy and daddy love them, you no longer love each other, but that you'll always be there for them.
If he's allowed access to the children it might be worth getting social services to supervise them.
I doubt very much if he'd get custody of the children at any point.
Also, you could speak to refuge if you need anywhere to stay to get away from him at anytime.