"I don't know how to write love letters," Frida Kahlo wrote in 1946. "But I wanted to tell you that my whole being opened for you. Since I fell in love with you everything is transformed and is full of beauty... love is like an aroma, like a current, like rain."

The renowned Mexican artist wasn't pining for her then husband, Diego Rivera. The love letter was intended for Jose Bartoli, a Catalan artist and political refugee who moved to New York after escaping the horrors of the Spanish Civil War. She and Bartoli met there while Kahlo was recovering from spinal surgery - a procedure aimed at treating injuries she sustained in a tram accident when she was 18 years old.

When Kahlo returned to Mexico, leaving Bartoli behind, the two embarked upon a secret, long distance romance, exchanging letters over a period of several years that touched on Kahlo's paintings, health and relationship with Rivera.

Twenty five of these love letters, written between August of 1946 and November of 1949, are headed to auction on April 15 at Doyle New York. Including over 100 pages of correspondence, the letters were originally saved by Bartoli until his death in 1995, and were subsequently passed down in his family. Today, they are expected to fetch up to $120,000 USD.

Despite living in separate cities and seeing each other only on rare occasions, the two artists continued a cross-country relationship for three years, exchanging sincere admissions of love, cloaked in deeply sensual and poetic writings.

"The Frida Kahlo archive is remarkably important," Rare Books Department Director Peter Costanzo explained in a statement to HuffPost. "Her letters to José Bartoli are entirely fresh and unpublished.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."