Several things happening here.
First, having something stuck into your body unexpectedly, without your permission, can be a shock, triggering fight or flight. A deep survival instinct that has no intellectual or higher element other than an instant reaction. The hit was probably an automatic part of that.
Don't do it again.
Second, a man can do a hell of a lot more damage with a hit than a woman or child can. Men have a duty to be aware of their potential for harm and control themselves, in general.
It looks like he failed there.
Third, he doubly failed when he didn't immediately stamp down his animal reaction and apologise for hurting you, for doing it in front of your child and frightening you both. That hit could easily have landed on your child.
Fourth, choosing to stamp out swearing instead was a triple fail. Not the behaviour of an adult, a decent husband and father.
Not sure of the timelines, but don't sit there stewing and sulking. Don't say to yourself 'if he doesn't apologise I'll ...'
Take control.
Firstly of yourself. Do you need any treatment for the hit? Keep an eye - if it bruises, take photographs. Keep a journal of date, time, incident. Is this the first and only time? Really?
Do whatever you need to calm and control your feelings, breathing, voice, language, body language.
And look to your children. They'll be frightened and shaken and need you.
And then take control of the situation. Take it into your hands, go to him and calmly say 'I'm sorry I shouldn't have done that, I understand it was a shock and you reacted, and I won't do it again.'
(Some will criticise this, but imagine if it had been the other way round, you'd hit him in reaction - and he apologised to you. That could open the conversation rather than shut it down).
'However, what you then chose to do hurt me and frightened me and the children.
We do need to have a conversation about that, about what happened in front of the children, and how we're going to put that right and make sure it never happens again.'
What he then says and does will then drive what you do next.
Just don't sulk, tiptoe or hope. Your children need to see you dealing with this. Do you have family and friends you can confide in?