I don’t understand why you wouldn’t leave a private school that was making life so difficult, or at least come to an understanding about how your D’s health issues were to be addressed during senior year before paying for another year’s tuition.
I agree with other posters that the first priority now is addressing your D’s mental health issues. The rest can follow in due course. If she has to defer the start of college for a semester because she hasn’t completed her high school course work, it’s not the end of the world. But to be honest, your D’s allegations of molestation by a doctor and of teachers yelling at her and talking behind her back suggest there might be some issues of confabulation here. Coupled with her downward spiral, I’d conclude that some serious psychological intervention is required ASAP, with the issue of finishing senior year put on the back burner.