If you get a Facebook DM (Direct Message) “who posted your photo?” with a link to apps.facebook – don’t follow the link.
Did you only click on the DM? It didn’t contain the payload. The “Play Video (Free Donwload)” [sic] post contained the payload, if you clicked on that link do not run the executable file.
Clicked on that one?
Don’t run the download. Oops too late … fair odds that the hack it is hiding as an app. Remove any unknown apps: https://www.facebook.com/help/204306713029340/
It is also worthwhile checking what the app gave itself permissions to access, it may need some further cleaning. If it came in via mobile there is also an SMS variant.