He was internationally renowned as a swaggering ladykiller who married six wives, fathered eight children and constantly outraged feminists with his macho pronouncements on women.

One of his mistresses, though, claims to have discovered a different side to Norman Mailer, the volcanic American novelist who died last November at the age of 84.

Carole Mallory, a former model and actress who met Mailer at Elaine’s restaurant in New York in 1983, suspected him of having an affair with a male friend, was worried that he might contract Aids and refused to indulge his fantasy of three-way sex with a gay man.

An archive of Mallory’s personal papers, recently bought by Harvard University, was shown exclusively to The Sunday Times on Friday. It contains a devastating portrait of Mailer’s sexual decline from world-class lothario to malfunctioning lover whose soon-to-be-former mistress wrote in her diary: “I feel so good not having sex with him . . . he does sexually to me what he likes done to him.”

At one point in April 1990, when Mailer was 67 and married to his sixth wife, Norris Church, Mallory worried that her lover of the previous seven years “could get Aids”.

Three weeks later, she wrote that Mailer had asked her what other men she would like to sleep with. When she mentioned a man named Paul, Mailer is said to have replied: “He’s gay. Why don’t we all three f***?”

At another point she writes: “He asked me to wash his bottom. So SAD. He is so ashamed of what he likes.” On October 24, 1990, Mallory scribbled in a black spiral notebook: “I think Rick Stratton is his lover. One of them.”

Richard Stratton was a convicted drug dealer who wrote a cult novel, Smack Goddess, based on his own experiences.

He and Mailer were close friends for more than 20 years and this weekend he laughed off the suggestion that their relationship was sexual.

“That’s an interesting thought, but there’s no truth to it,” he said. “I don’t believe there were ever any male lovers in Norman’s life at all. I don’t think he ever went that way, and certainly not with me.”

Stratton, who attended Mailer’s memorial service with his wife, Antoinette, earlier this month, said people often supposed that flamboyant heterosexuals were really “closet gays”, but he suggested that Mallory might simply have got it wrong.

“The outlandish claims of scorned women never surprise me,” he added.

The Mallory archive attracted international attention last week when it emerged that Harvard’s Houghton Library had bought seven boxes filled with hundreds of pages of letters and diaries and – potentially most intriguing – two long descriptions of her supposedly acrobatic love life with Mailer, one of them thinly fictionalised over 50 pages of a draft novel.

Mallory herself popped up in an interview with the New York Post to claim that the material was “very steamy” and that Norman was a “real man and he knew what he was doing”.

Yet the reality as depicted in her own handwriting is different. The sexual marathons of the early encounters – “One orgasm down. Two more to go? I hope so” – soon turned into tawdry sprints as Mailer, who by then was wearing a hearing aid and suffering from gout, dropped by for sex once a week. In return he got an earful.

“Why don’t you get me an apartment?” Mallory complains in one draft letter. “You are using me and conning me just to get laid . . . If you cared about me you’d pay my rent.”

Mailer eventually responds by inscribing a copy of one of his novels to “Carole, who is the worst f****** gold-digger I ever met”.

It is clear from the diaries that whatever Mailer may have felt towards men, he did not lose his enthusiasm for women, although his efforts went increasingly unappreciated by Mallory. At one point she declares that “sex isn’t really where it’s at any more”. In April 1989 she notes: “Sex awful. He tries, I don’t.” In February 1990: “I am happy to get [the sex] over with.”

Yet even as their relationship disintegrated, Mallory tried to cling to her famous lover. “I just like being with him, giving pleasure to him and seeing him happy,” she writes.

She told him in a letter: “Please don’t shut me out of your emotional life.” Later she added: “I’m so grateful to have him in my life.”

The archive is spiced with regular reports on the state of Mailer’s sexual apparatus. “He is hung like a stallion and so proud of it,” Mallory writes. “I love the pride he has with his awful body.” Yet as Mailer ages, he says he is getting smaller. “ ‘Do you measure it?’ I ask.”

It proved extraordinary and occasionally painful reading in a hushed library full of Harvard scholars, one of whom was poring over a volume of 15th-century sermons.

When the Mailer-like character in Mallory’s draft novel strips naked before her, she writes: “I gaze in wonder at his attributes.” When they begin to make love: “I chew on his cohorts of power.”

Mallory, now 66, never achieved lasting success as a model or an actress, but she developed skills as an interviewer of celebrities, and drafts of a proposed autobiography reveal that she slept with many of them. She lists 29 supposed conquests, including some of the biggest names in Hollywood (see panel).

In the early years of their relationship, when Mallory was trying to write a novel, Mailer helped her edit it. Leslie Morris, the Harvard library’s curator, said the main reason the university had been interested in so seemingly unacademic an archive was that Mailer’s hand-written amendments appeared on several manuscripts.

“The edits to me were the important things,” said Morris, who lost the biggest Mailer prize when the author sold his manuscripts to the University of Texas for $2.5m three years ago. “We don’t have that kind of money,” she said.

She declined to reveal how much Mallory was paid, but Mailer scholars may conclude it was worth every penny to read some of Norman’s amendments.

At one point Mailer changes his mistress’s prose from “stick that up your English tushy” to “stick that up your Hungarian bottom”. He also recommends that Mallory delete a reference to “nibbling his bullets”.

Mailer was generous with literary recommendations and contacts. Of her 50-page sex scene– which Mallory claimed she wrote on a dare from Mailer – the Pulitzer prizewinning novelist wrote: “I must tell you that the protracted sex scene is one of the best I’ve ever read, right up there and probably above Erica Jong and worthy of Henry Miller. He would have loved it.”

Mailer suggested she use his remarks as a blurb for her novel, but she never found anyone to publish it.

On September 7, 1991, Mailer telephoned his mistress. Mallory’s diary records the moment: “Norm calls to say, ‘Norris has found out. Can no longer see you.’ End affair.” But that may not be the end of torrid revelations about Mailer’s secret past.

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