Found: Fiction, Thriller, Stolen memories, Swan Lake Curse?

Need help finding name of book that is told from the point of view of a young widow grieving the loss of her husband. Her brother in law is later revealed to be her real husband/partner because her memories were stolen by her dead "husband". There's a bit involving the Paris catacombs and frequently references the curse of King Ludwig and Tchaikovsky (Swan Lake references).

Jasmyn, perhaps?

Yes!! Thank you!!!