Iconic Mexican artist Frida Kahlo is best known for her self portraits and recognizable beauty aesthetic. Well now the public will have a chance to become better acquainted with a more intimate side of the artist.

Twenty-five letters written by Kahlo will hit the auction block at Doyles New York on April 15. Unexpectedly, the letters are not written to Kahlo’s husband, muralist Diego Rivera, but to her lover, Spanish artist José Bartoli.

Kahlo meet Bartoli in New York while recovering from spinal surgery. Between August of 1946 and November of 1949, they carried on a secret, long-distance romance.

“Their love affair continued after Kahlo returned to Mexico, to her beloved home, La Casa Azul, and to her husband. The clandestine correspondence lasted for three years, aided by friends and Kahlo’s sister, Cristina, who had introduced the pair,” artdaily.org reported.

Kahlo biographer Hayden Herrera describes the unpublished letters as "steamy with unbridled sensuality,” according to artnet.com.

"Her letters to José Bartoli are entirely fresh and unpublished. They provide new information about one of the most important artists of the 20th century. It is an honor and a privilege to present this precious archive to the public. Its contents will surely further scholarship on Frida Kahlo and her works," said Peter Costanzo, the Rare Books Department director at Doyle New York,  to The Huffington Post.