“Truth crimes”: so the American poet Anne Sexton called the lies which peppered her turbulent existence, all of which — from possible incest to certain adultery and fatal depression — was unflinchingly, engagingly chronicled by Diane Wood Middlebrook during her decade's work on a 1991 biography.

By then 51, she herself found this book a turning point. Widely publicised, it led to her being asked to write the life of somebody of even more startling “truth crimes”: Billy Tipton, dead in 1989, had lived as one of the boys during a marginal jazz career while concealing from them, and five wives, that he was a woman — a fact only apparent a few minutes after death. Academia sloughed off, Diane Middlebrook felt liberated enough to immerse herself in the lives of Sylvia Plath and Ted Hughes, a man steeped in Ovid, subject of her last book.

Born in 1939 in Pocatello, Idaho, daughter of Thomas and Helen Wood, both of a modest medical background, she was brought up in Spokane, Washington. At the age of 8 she had a poem published in the local paper — foreshadowing the literary studies which, to her parents' dismay, eventually took her to the University of Washington at Seattle.

After graduating in 1961 and separating from her first husband, Michael Slough, she began a PhD at Yale, simultaneously teaching at Stanford and marrying fellow-academic Jonathan Middlebrook.

Of her “pathetic” 1968 thesis on Wallace Stevens and subsequent, scarce Walt Whitman and Wallace Stevens (1974), Middlebrook said “I don't recommend anyone try to read it.” Female and tenured, however, she became head of Stanford's new Institute for Research on Women and Gender; more informally, she and colleagues created a Crow Group whose discussions fostered far wider academic, and publishing, topics, such as Marjorie Garber's cultural studies. Divorced in 1972, with a six-year-old daughter, she continued with academic books — including Worlds into Words: Understanding Modern Poems (1980), about modern poetry — before the new liberal atmosphere prompted Linda Gray Sexton to ask her to write her mother's life.

Middlebrook said that she counted herself “among the people who didn't much like Sexton's public persona. I liked the project, though, because Sexton's career posed big, interesting questions: How did a mad housewife become a star? What connected her madness and her art? Why did her work appeal to poetry avoiders?”

As with the Billy Tipton book, she paid tribute to journalists' help in learning where to find people and sources; she also drank six early-morning cups of coffee: “that's my drug; it makes me feel elated and smart. I have learnt not to lavish that precious illusion on reading The New York Times straightaway.”

Unusually, controversially, she was given hundreds of hours of Anne Sexton's taped therapy sessions, which — “truth crimes” or not — related the torments suffusing the poetry she began at the age of 27 when, after a suicide attempt, she chanced upon an inspiring televised Boston lecture by I. A. Richards. In drawing together so much about a poet who had killed herself in 1974, Middlebrook felt as if she herself had learnt to write.

In 1985, while busy with the Sexton project, she married Carl Djerassi — 16 years her senior, he was a professor of chemistry who in the 1950s had helped to develop the first oral contraceptive pill. This work had brought him considerable wealth, and he was a noted Klee collector. However, the suicide of his artist daughter and discussions with Middlebrook prompted him to switch to supporting living artists and to exchange science for writing novels and non-fiction.

Their life was far removed from that of Anne Sexton. They divided their time equally between San Francisco and London, and in both cities they were generous with their time (also creating various foundations), believing that writers gained from congenial, talkative rooms.

Middlebrook exuded charm and energy, a delight in life, and was spurred by such discussions as she worked on Her Husband: Ted Hughes & Sylvia Plath, a Marriage (2003), as well as navigating the American paths, familiar from childhood, taken by Billy Tipton. Invited to write Suits Me: The Double Life of Billy Tipton (1998) by Tipton's family, she drew upon conversations with some who not only knew her but, without prurience, established the extraordinary means by which she satisfied those who were certain their husband was a man.

Middlebrook stepped down from her position as Professor of English at Stanford University in 2002. Always a believer that teaching and writing should be supported by wide reading, she had long been fascinated by Ovid's Metamorphoses. That poet, about whom so tantalisingly little is known, was the subject of her last book, which will be published as Young Ovid next year.

Diane Middlebrook, literary scholar and biographer, was born on April 16, 1939. She died from cancer on December 15, 2007, aged 68