Unfortunately, I have since found out that this is not genuine.
https://www.reuters.com/article/uk-fact ... SKBN21733X
This is parody written by American author Nick Farriella for the humor site McSweeney’s earlier this month. The text is clearly identified as such at the bottom of the original online publication and now at the top: “NOTE: This is a work of parody and is not an actual letter written by Fitzgerald.”
Here's a link to the original piece:
https://www.mcsweeneys.net/articles/thi ... -of-france
Apologies folks but all is not lost as I also found this:
https://www.mcsweeneys.net/articles/fam ... oronavirus
I suppose an online parlour game might consist of someone guessing the original novel from the parody and I would expect that Bram Stoker, Stephenie Mayer and Charlaine Harris might then feature prominently.