I know in real life, James and David were still together when James drowned and it was David who found him floating. So, does this movie just make up the gardener and housekeeper characters, or were their parts in his final days just exaggerated?
Where did you learn that Whale and Lewis were still together at the time of his death? I'm not sure that's accurate. I believe Whale's last lover in life was Pierre Fogel.
GODS AND MONSTERS is based on the novel FATHER OF FRANKENSTEIN by Christopher Bram. The poetically-named Clay is a creation of Bram's, though may be seen to be somewhat based on Whale's French lover, Pierre Fogel. I may have the spelling of his name wrong.
Whale had two Hungarian housekeepers, Hannah and Johanna - again, I may not have their names spelled correctly - which the screenwriter and director Bill Condon merged into Hanna, played by Lynn Redgrave. Bram's housekeeper in his novel was a fictionalized Mexican character named Maria.
Get that book and turn to chapter 32, page 384: Whale's maid Anna Ryan found the body. I do think it's true that Lewis didn't disclose the note until years later, via an earlier edition - perhaps a monograph - of the above biography.