I spent 7.99 on the kindle version of this book.
My partner and I had discussed chastity several times in the past but my cage didn’t fit right and she didn’t really know anything about it or understand my motivation.
I bought that book and gifted it to her after I bought a properly fitting cage. I then surprised her with the cage on one day and sent her the book. She read it about a week or so later and it was honestly wildly successful. She loves the way I behave when I’m in it, all the attention, and just everything about it honestly. She is clearly enjoying the dominant role and she enjoys that I am visibly happier. If it weren’t for that book I truly don’t think we’d be here.
It starts off very gently and only briefly references the humiliation/sissy etc etc etc aspects of it maybe once or twice. You can Google a PDF for the book and preview it and you’ll see what I mean. I really think it’s the perfect solution for your problem.
I'm going to recommend you start with books geared to new vanilla women.
Lucy Fairbourne "A guide for keyholders"
Sarah Jameson "Be careful what you wish for"
Dossie Easton & Catherine Lizst "When somone you love is kinky"
The last one is not specifically about chastity, but is an excellent read for those who do not understand kink.