Hm.
On the one hand, what Shizuku did was really, really bad. No way around it.
But on the other, if the other kids wanted to stop it they should have just said so. She wasn't doing it on purpose, she just thought she would help Ruri by openly saying what the others were all talking about behind her back anyway. So honestly they are also at fault.
Most importantly, its not like Shizuku just brushes aside what happened. She never intended to bully her in the first place, and now the guilt of it is literally destroying her.
I do wonder what exactly Asaka wants though.
And I really need to know what that letter said.