Hi and welcome - and yes you are right - sadly there are many people in your situation. It seems that your exgf's motive is revenge and jealousy - or she may have been following the news and found out about the compensation she could get.
Simonsimple's advice is spot on. And I would endorse saying nothing to the police unless it becomes necessary. If you go and tell them your ex is making these claims they HAVE to investigate and they will believe her because they have conviction targets to meet.
There are things you can do though, and as SS has said, back up all copies of the info you have and store it electronically somewhere where plod can't get it; (if she does go to them they may seize your electronic stuff). Monitor her FB and other social media posts and screenshoot anything and everything that you think could be useful to you. Don't contact her or comment on anything she has written. She will use it as evidence against you if she decides to take it that far. You could also start looking for specialist solicitors in your area. There is a thread in the "Useful Information" section of this forum.
So, sit tight and hope she doesn't follow up her rumours.
please keep posting and let us know what happens and we'll help all we can