Proust, turned her into a fictional princess and Ravel turned her into music. Renoir and Toulouse-Lautrec couldn’t stop painting her. Picasso was a confidante, Serge Diaghilev of the Ballets Russes, a best friend, and Coco Chanel – her “soul sister”; possibly her lover too. Belle Epoque Paris bloomed with opulence and a languid, if not…