I think this would depend for me on lots of factors.
What is your DH's attitude to it - does he think it was a problem, want to work on changing how he responds in future etc
What kind of hitting was it, I think a full-on punch is different to a spur of the moment frustrated little slap. How much aggression was there, basically
Is this part of a general pattern of behaviour of your DH being controlling, aggressive, unpleasant, demeaning etc
Were there any other factors that made your DH less able to control himself - stress from illness, money etc, that could be addressed
I don't think you should throw your family away for a single isolated incident, it depends whether it will be an isolated incident. I think violence to children is different to violence to partners. You do need to be in the role of punishing/disciplining children and you can't just walk away if your child is unpleasant, unlike a relationship.