L & C, His telling you that if you do this, then I will do this, is his way of twisting this into being able to blame you for his bad choices and decisions. It is pure manipulation and a way to force your hand into keeping his secret. If you are worried that you will be retaliated upon for exposing his affair, then there has to be some way to make an anonymous phone call to someone that would be able to spot some sort inappropriate action between the two of them. Do you have any friends that work or volunteer at the school?