She appears to have hit him first, so his equal-force-applied physical rebuttal is perfectly fine. 
In this Equality (Clown) World, that’s the expectation, yeah?
You can’t have it both ways. 
Regardless, a couple of middle-aged goobers drinking too much at an obnoxious shindig and becoming jarred loose from appropriate behaviour. 
Kiss and make up and call it even. 
Case closed.