my brief opinion on this
of course the teacher will be fired, he abused his position of power over a student. A teacher is not allowed to have sex with students, not even with adults. It is not legally punishable, but the school does not have to accept it and will not do so. of course the school can also take all the consequences it can against Jane, as long as there is a possibility that she can still graduate from school (which is obviously the case)
In my opinion, the chastity belt is completely wrong here. It makes the problems even bigger. Monica and Jane don't trust each other and a girl in the belt has to trust the key holder, otherwise it won't work. In my opinion, therapy would be the best approach here.