A teacher is supposed to if they follow protocol. However, it wouldn’t just be your parents, it would be guidance, social workers, counsellors, etc to help you. A teacher can keep some things confidential, but anything you tell them that involves the harm of yourself or others, they need to bring it to others for the good of everyone.
If you are feeling suicidal, please reach out to someone you trust who can help you and put you in the right direction.
Teaching In Real Life 