How was this hit different to a spank?
Quite frankly, I was spanked as a child, and ive been hit many times as an adult. The difference to me is : a spank is a open handed 'smack' for lack of a better word used to give a short sharp shock. No bruises as a result, but a lesson learned.
A hit on the other hand is a closed fist or a really hard 'smack' designed to hurt, intimidate and humiliate.
What you have described is a spank.
Quite frankly being spanked never did me any harm, and in your husbands shoes I would have spanked her too.
Spitting is disgusting and at 3 she should already know not to do it. But as she clearly doesn't, a discussion about it being wrong won't do anything as she will have forgotten what she did wrong within a minute. Whereas she will now associate that behaviour with a light spank and it will hopefully deter her spitting in the future.
Spitting is now technically classed as assault, so it's probably best that it's nipped in the bud now.
I personally will be spanking my children when they deliberately do something naughty until they are at an age where they can hold a discussion 're right and wrong and understand the difference properly.
Lack of discipline is rampant now a days, sometimes children are nasty, and if they don't get immediate consequences they continue to be nasty, and they grow up into nasty teens and adults.
I'm not at all saying your child is or will be nasty like I mentioned previously. But God I know a few people that would have turned out differently if they had been disciplined properly.
In summary, get a grip, he disciplined his child how he saw fit when she spat on him. He was unpleasant to you because you undermined him infront of his child. It was a light smack. Not a black eye.