Caitlyn Jenner wanted a sex change decades ago, the retired Olympian’s former wife, Linda Thompson, reveals.

In Thompson’s new memoir, A Little Thing Called Life, excerpted in People, the mother of Brody and Brandon Jenner recalls her ex-husband’s early struggles with identifying as female.

Thompson, who famously dated Elvis Presley before marrying Jenner in 1981, reveals that it was in 1985 when Jenner confessed he identified as a woman. Recalling the moment in her memoir, Thompson says Jenner told her: “I am a woman trapped in a man’s body.”

Related: EXCLUSIVE: Bruce Jenner’s Second Wife Linda Thompson Commends ABC Interview

Thompson writes, “‘Whoa, Bruce, honey, have you looked in a mirror?’ I protested. ‘You are the epitome of the ideal man!'”

She says Jenner responded with “I have lived in the wrong body my whole life. It is a living hell, and I really would like to move forward with the process of becoming a woman.”

Thompson reveals that the couple went to therapy in the hopes Jenner would change her mind. “As we tried to work through our feelings,” Thompson recalls, “Bruce told me he was considering travelling out of the country, possibly to Denmark, to try to have the gender reassignment surgery anonymously and then come back as a female.”

Related: Caitlyn Jenner Looks Back At Olympic Glory In ‘Sports Illustrated’ Cover Story

Thompson notes how she kept Jenner’s secret for years, and refrained from telling their sons. “I felt such an obligation to keep Bruce’s gender dysphoria his secret that I did not even tell my sons until they were 31 and 29 years old, respectively,” Thompson writes.

She adds, “I wanted them to experience enough life and garner enough knowledge, confidence, and compassion to be able to deal with their father’s true self.”