Accusation on Facebook that never made to court

Hi my friend has been accused of multiple things from assaulting his child to sexual assault of his ex, after short investigations from multiple specialist detectives, all matters were not deemed viable for court due to insufficient evidence. Now the ex has written a extremly long and graffic accounts of her accusations that bore no evidence on Facebook, however she didn't mention his name and asked for no one to write his name but many comments from 40+ people know who she is talking about. He has mass amounts of evidence against all these allegations. Where does he stand ie is it a matter for police or straight to solicitor.