Legal Question in Criminal Law in Massachusetts

Re: Do I request a hearing?

You are correct that it is a crime to knowingly make false A&B allegations to the police. If there is probable cause to believe that the "victim" did this, then a criminal complaint could issue against that person and criminal charges brought. Assuming this situation is as clear cut as you indicate, my suggestion is that you first contact the police and see if they will bring this charge to the court's attention (thereby taking responsibility for following through with this off of your shoulders). If they decline to do so, you would have the option of pursuing these charges yourself, by filing an application for criminal complaint with the District Court. (The Clerk's Office has the form that you fill out to do this.) That will result in a hearing before the clerk magistrate with you and the victim and any witnesses who show up and can shed light on the issue, at which time the clerk magistrate will determine whether there is "probable cause" to believe the victim commited the crime of knowingly filing a false police report. If the clerk magistrate determines that there is in fact probable cause, then a criminal complaint will issue, and the victim will ultimately be arraigned and have to face charges. If, on the other hand, the clerk magistrate rules that there is not probable cause, then no criminal complaint will issue, and the case will be dropped.