Please, please, PLEASE report her. It is NOT something you have done to set this teacher off. As a teacher, she is supposed to report her findings of a student in trouble, but, it seems to me, like she is making that comment so you hide it and then she no longer feels forced to do something about it, or wouldn’t get in trouble for not doing something once someone else discovers it.
Go to a teacher you have a good relationship with. Tell them your struggles and why you are offended by this teacher. You will have to discuss your cutting; I would hope you could get some help, but you won’t be forced to do anything you don’t want to do. This teacher is avoiding her responsibilities of a teacher, and is placing even more struggles onto you.
Once you report her, it may seem like it was for nothing, as, to you, it might not seem like anything changed. Situations like this with teachers take some time for there to be any significant action against them. Be patient.
I see situations like these as “meant to be.” You were meant to be told this by the teacher in order to help other students who may hear similar comments from her, and it may just be the situation that allows you to seek help.
Do whatever you feel is right. You can report her by still keeping some secrets about your struggles, but I would hope you could get some help. Teachers who are there for the right reasons would NEVER see your cutting as trying to get attention or something that puts the teacher in an awkward situation. Good teachers WANT to help, and this job requires more than just academic help. Your situation will be dealt quietly and effectively by a proper teacher and administration. Go to someone you feel absolutely comfortable with.
I hope this helps.
Teaching In Real Life 