ATLANTA — Love letters written by Sylvia Plath’s husband to his mistress have been acquired by Emory University’s Robert W. Woodruff Library.

Despite writing to Assia Wevill to “please burn all my letters,” the collection includes more than 60 letters from British poet laureate Ted Hughes to Wevill and six from her to him — as well as a number of notes, sketches, fragmentary diary entries, and a few photographs of Wevill.

The correspondence “offers readers unprecedented access to Hughes’s state of mind at a time of crisis in his personal and professional life,” the director of Emory’s Manuscript, Archives, and Rare Book Library, Stephen Enniss, said. The letters were added to the Hughes literary archive at Emory, which the library acquired in 1997.

Plath, who documented her struggles with mental illness in her autobiographical novel “The Bell Jar,” killed herself in 1963 at age 30 after discovering her husband’s affair.

Six years later, Wevill killed herself and her 4-year-old daughter in a manner that resembled Plath’s death.

A few weeks after Wevill’s suicide, Hughes wrote to her sister, Celia Chaikin, to say that their life together had been complicated by “old ghosts” but adds, “Assia was my true wife.”

In another letter, he told Wevill, “You’ll see that I’ll fulfill all my promises eventually.”

Hughes was Britain’s official poet between 1984 and 1998, the year he died.