When the nephew spat on the OP, the OP reacted instantly by striking the nephew lightly on the back of the head with an open hand as he walked past. The immediate aftermath saw the rest of the family become very upset with the OP for disciplining a child who was not his own, leaving the OP questioning if his reaction was an overreaction given the disrespectful act he endured.

I (34 M) smacked my nephew (14 M) today after he spat on me at the dinner table.
I was sitting at the dining table with my family this afternoon, and my nephew was squirting saliva out from underneath his tongue at people. When he did it to me, I was immediately grossed out and jumped up to go and wash myself.
As I was walking past his chair, I clipped him over the back of the head with an open hand. I did not hurt him, nor did I really think much of it at the time – but my family are very upset that I disciplined another person’s child.
I’m not an abusive or aggressive person, but I am left feeling really bad about this situation. Is it fair to say that I overreacted? My nephew is about 3 inches taller than me and I sometimes forget that he’s still a child.
I just felt very disrespected for being spat on.
Conclusion
The OP is currently feeling distressed because his defensive reaction to being spat upon—an act he viewed as highly disrespectful—has led to strong disapproval from his family members who believe he overstepped by physically disciplining another person’s child.
The core debate centers on whether a strong, immediate physical reaction to being deliberately defiled is justifiable self-defense against disrespect, or if it represents an unacceptable overreach of parental authority in a family setting, regardless of the provocation.
Here’s how people reacted:
I think you should say to your family it wasn’t the best idea and you reached out of anger cuz you were so disgusted and it won’t happen again.
that he had been grossly inappropriate. You did right.
HE SPAT ON YOU FFS.
He’s lucky it wasn’t me.
Ask your critical family and friends
if they would like you to spit on them.
Ask them how they’d enjoy it.
Here in the uk it’s actually assault
You’re NTA. You should have slapped him harder.
He’s not a ‘child”, he’s 14 and unless he’s been diagnosed with the IQ of a 3 year old, headed for trouble.
He’s14 for God’s sake. At a table no less??? Where are his guardians to smack him for literally spitting at others??