The shit they did was more than picking on her verbally.

If I remember correctly it started with verbally bullying her with focus on her dead father which is super messed up and then deceived her to publicly humiliate her.

While this is of course still not physical and her reaction is over the top I don't believe you have to wait for your bullies to start beating you up until you are allowed to fight back.

Like, you said "walking away".. Beeing an asshole in school is bad enough but going out of your way to make someone elses life worse even in her free time? Get fucked.

Zero empathy for that character.