Some of his correspondence with the married French Duchess survive. I haven't yet found the texts online, but they might be worth perusing.
http://https//www.unz.com/p…PDF&apages=0099
From the text: "William Short, Jerfferson's 'Only' Son"
Much of his writing to her was burned sometime during the Reign of Terror, though few have survived. The small, formatted text denotes the contents of letters, followed and succeeded by chronology and context of each letter.