Well, it also depends on the outcome. If she dies, trust me, he will be found guilty (or will plead out or something). Furthermore, I do not know how a jury will 100% perceive it. However, we knows how society views such situations. Do you really think if she dies, he is not going to either plead out or be convicted? lol haha. Oh boy. This happened in NEW JERSEY, NOT Texas or Arkansas. You obviously do not know the distinct local cultures by state.
Hell, in NYC, a robber tried to enter a MANS HOME and he shoots intruder and is charged with manslaughter (story can be found on google). And you actually think a women hitting a man in the face, and him laying her out, and if she dies, he won't be convicted?

Now this is New Jersey, which states: the amount of force which the defendant uses must be necessary – this defense is unavailable if the actor is unreasonable in his belief about the amount of force necessary and if acting on this unreasonable belief the actor uses an excessive amount of force.
I can guarantee you a Jersey Jury will not believe the force was necessary, especially after viewing her hospital and funeral pictures.
You can waffle all you like, you keep quoting legislature that validates my argument in the mistaken belief it helps your point of view.
The guy got punched and he punched back, do you seriously think that he thought the legislation through prior to hitting her.
He believed punching her was required to protect himself and acted on that belief.
Now in hindsight he probably still thinks he was in the right to punch her but wishes he hadn't.
Her injuries were most likely caused when she hit the pavement not from the punch, I know that but for his actions she wouldn't have hit the pavement but alternatively but for her actions she wouldn't have been hit.
The law is an ass in cases like this and its about whats morally right that I'm concerned about.
Let me give you a similar question that Board Sheriff ran away from.
Imagine yourself sitting with the grieving parents of the young man in the scenario, he didn't hit the girl back and she hit him again and he ended up dead as a result.
The father says, "if only he had hit her back he would be alive today"
Now, do you say "thats unacceptable, he shouldn't hit a woman"