@SJ7 is she really a bitch tho?
From her perspective Ishigami kinda just beat up her boyfriend out of jealousy and the boyfriend dumped her out of fear of him. She was enough of a good person to Ishigami before to make him change his mind about being bitter to everyone around him.
If anything she's weird for not being more angry.
Literally imagine the quiet kid with a sharp tongue you had been nice to beat up your hot af boyfriend/girlfriend and then that said person broke up with you because of them.