Honestly, It's hard to feel very bad for her. Yes, she had crazy mommy issues. But she actively harmed and hurt other people who got in her way just to get some praise. I empathize with her shitty situation and lack of a good parental figure, but she brought all of this on herself. She didn't have any real friends and never chose to reach out. She is so used to putting people down to get higher that she was unable to function otherwise. Anybody with a brain and isn't fucking dominated by ego or just stupid wouldn't have fucked with the model student when she got precious dirt on you in a SINGLE FUCKING DAY. Like Touko probably never even talked to her once, but a single glance at her dad made her do all of that.
And at the very end, you refused to see the consequences of your actions. She wasn't a 12-year-old or younger who really couldn't understand those types of things. She just ensured herself everything was Touko's fault. She was a danger to herself and others.
Feel that her end is truly karmic.