If she made threats of harm, that is a crime and you can report that to the police. If she defamed you (and that is a complex deterimination) you can sue her. To see if there is a basis for a lawsuit, see an attorney. You say "the damage is done." What damage, exactly. Do you really thing anyone anywhere believed her at all?
We do not have a client/attorney relationship until you make an appointment, we discuss your case face to face, I accept a retainer, and we explictly agree to enter into representation.