It is called “Trapped and Trained” by Christy Anderson. I seems like it has been out of print for a while, but I’m sure that there is a copy somewhere. I don’t even need a physical copy, just a copy.
It seems as though part of it was posted to Literotica, but it stopped short about 10 years ago.
I don’t have much hope but I know the internet has its ways, so I am reaching out for help. Let me know if anyone finds anything.
Source: reddit.com/r/eroticliterature/comments/qqzjxs/looking_for_a_book
google it, there’s lots