NEW YORK>> Mimi Alford was terrified in 1998 when the Monica Lewinsky scandal turned the word "intern" into a dirty joke, exposing an affair with a president. Her decades-old secret about her trysts with John F. Kennedy was still safe then.

Outed in a 2003 biography and a New York newspaper account, Alford has learned to tell her story and not be ashamed of it — from the moment she said Kennedy seduced her on her fourth day working at the White House until the affair ended shortly before his death.

In "Once Upon a Secret: My Affair with President John F. Kennedy and its Aftermath," published last week by Random House, she writes of her first encounter as a naïve teenager, her "varied and fun" sex life with Kennedy, whom she always called Mr. President.

The Rumson, N.J., native was 19 and had no sexual experience when she first went to bed with Kennedy in his wife, Jacqueline’s, bedroom. It was June 1962.

"Short of screaming," she writes, "I doubt I could have done anything to thwart his intentions."

Nor did she want to thwart his intentions.

"I wouldn’t describe what happened that night as making love," she writes. "But I wouldn’t call it nonconsensual, either." Addressing people who have questioned the encounter, she said: "I don’t consider it was rape. I have never considered it rape because I was willing."

The relationship continued, even after Alford had become engaged while attending college in suburban Boston, until Kennedy’s 1963 assassination, she wrote.

The two raced rubber ducks in the bathtub; they had multiple sexual encounters, though he never kissed her; when he called her at her college dorm, he would use the code name Michael Carter, she wrote.

Her account seems "quite credible," said Robert Dallek, whose Kennedy biography made a passing reference to a college sophomore who was a favorite of the president’s.

"This is how he operated," Dallek said. "He was a compulsive womanizer."

A lawyer for the Kennedy family did not respond to requests for comment over the weekend.

Writing the book was liberating, Alford said in an interview last week in her publisher’s midtown Manhattan offices. Now 68, Alford was slim and elegant in a gray knit dress, gray pageboy hairstyle and pearl earrings.

She was Marion "Mimi" Beardsley when she arrived at the White House press office the summer after her freshman year at Wheaton College in Massachusetts, then an all-girls school.

The affair began during her summer internship and continued when she returned to Wheaton in the fall, she wrote. It continued while she dated and until a few months after her engagement to Tony Fahnestock, a senior at Williams. She was deep into wedding preparations when Kennedy was shot.

Overcome with grief, she confessed the affair to her fiancé. He told her never to breathe a word of it. She promised, fearful that the only alternative was to break off the engagement, and she largely kept the promise, telling only a trusted few. It took years for her to see the connection between her silence about the relationship and "the emotional shutting down" that had blighted much of her life.

"I needed to look at the secret and then look at the impact of having kept the secret for so long," she said.

Mimi and Tony Fahnestock divorced in 1991 and he died in 1993. Alford married again in 2005, to Dick Alford. Her two daughters from her marriage to Fahnestock are in their 40s, are mothers themselves and have supported her decision to write of her experience, she said.

The book took several years and multiple drafts. Alford supplemented her memory with research at the Kennedy Library, where she found her name on passenger logs from plane trips with Kennedy’s entourage.

The story she tells is not always flattering to Kennedy or to Alford herself.

She felt no guilt, she wrote, with regard to the first lady, whom she never met.

"I do now," she said.

But at the time, "it wasn’t as if I was trying to replace her or that the president was trying to replace her. I think I just went along. And so I didn’t feel guilty. It’s kind of embarrassing to say that."

Alford knows that readers may judge her harshly; "it doesn’t frighten me," she said.

She describes Kennedy as "a kind and thoughtful man." And then, she tells stories of what she calls his darker side.

She says Kennedy once asked her to "take care of" his aide Dave Powers, who had served as the go-between facilitating the affair; she performed oral sex on Powers while Kennedy watched. The president later apologized to both of them.

On another occasion, she wrote, he asked her to do the same for his brother Teddy. She refused.

Then there was a party with a "fast Hollywood crowd" at Bing Crosby’s house in Palm Springs, Calif., that she attended with the president. A guest offered yellow pills that she believed were poppers, or amyl nitrate, a drug often used to enhance sexual pleasure.

Kennedy asked her if she wanted to try one and she said no, but she said he popped the capsule and held it under her nose anyway.

"Within minutes of inhaling the powder, my heart started racing and my hands began to tremble," she writes. "This was a new sensation, and it frightened me. I panicked and ran crying from the room, praying that it would end soon."

Alford debated whether to share episodes like this, taking them out of the book and putting them back in. If she had excluded them, she said, "it would have felt like I was not telling the whole story."

When the affair with Kennedy was revealed in 2003 — the Daily News of New York published her name — Alford spent a few days holed up in her apartment with the media camped outside. Then they left and she started going to work and going grocery shopping again.

After interviews to promote "Once Upon a Secret," she expects to return to her quiet life once more.

"It’s sort of like closing a chapter on that 18 months," she said, "and closing a chapter on keeping secrets."