you can file a FIR online without let your family know that
First calm down..
and yeah wakefulcow1 is correct
if you are a minor seek help fo someone who. you trust
Don't let suicidal thoughts reach your mind
try to tell your sibling if anyone is elder
Lodge an FIR with the police. Your identity will be anonymous
Don't hesitate tell me your city, if possible I'll provide you contact number of police officials who will sort it out without causing any harm to your personal life,you both will be called in office and they will create evidence that he was blackmailing you and they will not lodge FIR,in future if he doesn't change his mind and try to do the same thing then you can lodge and that police official will support you in court