It's possible you're thinking of one of her other works, such as:
* "The Bloody Chamber and Other Stories" (1979), which includes a story titled "The Mirror of The Jealous Woman"
* "The Magic Toyshop" (1967), which has themes of mirrors and reflection.
It's also possible you're remembering a book with a similar title.
Please clarify the title or provide more information so I can help you find the book you're looking for.