It's best for the kids too because you don't want to raise them thinking this relationship is normal. Or they'll grow up and end up in similar toxic relationships.
I'd be inclined to tell him it's over because you dont want to be in the relationship anymore. Don't be drawn into why. Just make statements like 'I don't want to be with you anymore'.
If hè gives it some shit like 'don't you want to work on it? What about the kids?' then you say 'No. You had enough chances to work on it. I'm done'. Any follow up from him, then reply 'it's over. I don't want to be with you anymore'. Repeat repeat repeat.
Don't give him any whys he can use to manipulate you. He will try to goad you.
You don't owe him any explanations. You don't owe him more chances. You don't need his permission or agreement to end the relationship.
'I don't want to be with you anymore' is a perfectly acceptable reason to split up.
Besides, he absolutely knows WHY. He'll just pretend otherwise. Don't get sucked in. Easier said than done of course.
But remember this- being brought up in a home seeing their mother abused is not a healthy home for the kids. So Don let him break you with the 'you're tearing our family up' troupe. Leaving him is PROTECTING you family.
People who abuse you are not your family.