Thr allegations are twofold: first - when his trainer was knelt down inspecting his foot for a fracture that he slid forward and jammed his testicles onto her head. There is also some other incident that is redacted from the public record.

He tried to cover up the incident and got her run out of Tennessee. Later he and his father concoct a damaging series or stories about her and include them in a book. The trainer sued and in court records it is pretty well established that the Mannings lied and knew that they were lying

Her defamation lawsuit settled out of court. My guess is she got a decent settlement in return for staying quiet.