What to do if a girl does not want to get tested for pregnancy?

This is the issue, I was engaged, the guy cheated on me, had un- protected and know he does not now if she is pregnant. I no longer with him but she keeps calling me to tell she is pregnant, but she does not want to show the results? Could she be bluffing? I told her I would make a police report if she kept calling. And I ask him to tell her to stop. I am stuck in the middle, and he wants me back but he is not sure of her pregnancy!