One of my roomates when I was younger was accused of a bad deed and the police came to arrest him and talk to me. He was arrested for said crime and then the accuser told the police she lied and made the whole thing up about 3 days later. His parents had already spent a few grand on an attorney and I got grilled by the police for hours. What an experience. The main detective did believe us even though he had to do his job.
Yeah, that sucks. Your buddy could have sued her for damages I think.