Of course he was ready to fight she threw the first punch. Do not start what you can't finish. If the dude wasn't a pathetic weakling and actually got her back harder than what she could dish that would be a lesson to not start random fights with people just because they said some mean things to you in a video game.
The fact him trash talking her in a video game and she resorted to violence puts her way more in the wrong than him. If you really think there's an equivalency to mean words on the Internet making notice on how bad you are at something vs beating someone up because someone pointed out your failings. I don't know what to say other than take their words and get gud or ignore them. You look more pathetic trying to beat up someone just because they're harsh in their criticism towards you.
It's just a punch, dummy. It's not like she cut off his arm or something, he'll be fine, and he actively provoked her. She'd be fine if he succeeded on the hit, too.
Ideally no one would be provoked and the world could be nice and peaceful, but 'provoking' wouldn't even be a word if everyone was just immune to shit talking.
Make someone mad and they might just react to that fact, him getting up and trying to throw a punch wasn't "self defense" just because he called it that, it was him now wanting to fight and seeing himself as justified, the same way she probably felt pretty justified from his words.
If we really wanna talk about leaving things at just words, then he shouldn't have come to a meet up with someone who said they wanted to beat his ass up front. Pretty pathetic to see someone wanting to beat your ass cause of trash talking, then continue to trash talk in person without any self awareness.