The sensei is so fcked up, she knows Reiji didn't do it with Chako but she still wants to get rid off her.
I guess the sensei see a teenager as a rival, she really risked too much when the sensei is the one who has more too lose cause she slept with her student.
At this point I don't mind if Reiji suicide or find the salvation with someone, I just hope for Chako to leave the town and be happy~