Seems we now have some serious competition for Gendo Ikari in the Best Dad 2020 category... "Have I not fucked up your life enough yet? Hold my briefcase."
And of course the school's gonna know. Things like that spread really fast. The rumormongers in class would have a field day with that: first she's caught doing "kinky sh*t" with another girl in school, then her dad jumps under a train on the very same day. Coincidence? I don't think so! That's an immediate outcast status for her.
And being an orphan and minor, I guess what follows is being put under care of some other relative.
EDIT - looking again, I think he rather jumped on the following day, not the same day.