For hours, the lawyer, Donna Rotunno, had pressed Ms. Mann on cross-examination about the details of consensual sexual trysts she had with Mr. Weinstein before March 2013, when Ms. Mann says he raped her.

The email that triggered Ms. Mann’s tears, written in May 2014, attempted to explain her relationship with Mr. Weinstein to her boyfriend. “Sometimes I felt hopeless and that I should just be with an older man because I’m a lost cause,” she wrote.

She said Mr. Weinstein had given her “all the validation I ever needed,” offering to buy her things and give her money — offers she said she rejected. He “always offered to help in ways that my parents didn’t,” she wrote in the email.

“I tried to make him a pseudo father,” she read.

“This sexual assault was from when you were younger?” Ms. Rotunno asked. Ms. Mann, distraught, was unable to answer.

Ms. Rotunno also focused the jury’s attention on a series of friendly emails Ms. Mann sent to Mr. Weinstein after the alleged attack, saying things like, “I appreciate all you do for me.”

“You manipulated Mr. Weinstein every single time — as manipulated as you claim you felt — isn’t it true?” Ms. Rotunno asked, adding that Ms. Mann“continued to see him after every sexual encounter, is that correct?”

Ms. Mann acknowledged she had manipulated Mr. Weinstein to protect herself. “How I handled it to survive and process it — yeah, I guess you could say it was manipulation,” she said.

Ms. Mann, 34, said she had maintained a relationship with Mr. Weinstein, the once-powerful producer, to protect her career, adding that she worried about his “unpredictable anger.” She said she had consensual sexual encounters with Mr. Weinstein after long negotiations, despite not wanting to do it.

On Friday, Ms. Mann testified in excruciating detail that Mr. Weinstein had trapped her in a New York hotel room in March 2013, where he ordered her to undress, menaced her and then raped her. “I gave up at that point,” she said

She said he attacked her a second time eight months later at a Los Angeles hotel, where she was working, after she told him she had a boyfriend and wanted to end their relationship. He ripped her pants off, screaming “You owe me one more time!” on that occasion, she said. He is not charged in New York in connection with that incident.

But Ms. Mann also said that before the alleged attack in New York, she had an “extremely degrading” relationship with Mr. Weinstein that included some consensual sex acts, though not intercourse.

Ms. Mann is the fifth accuser to take the stand against Mr. Weinstein in his trial in the State Supreme Court in Manhattan. Mr. Weinstein has pleaded not guilty to five felony counts. He is charged with first and third degree rape, and one count of predatory sexual assault, which carries a maximum penalty of life.

Six women have agreed to testify that Mr. Weinstein sexually assaulted them. The heart of the criminal indictment is based on the accusations made by two women: Ms. Mann, and Miriam Haley, who testified that he forced her to let him perform oral sex on her at his home in 2006.

Prosecutors are using the account from a third woman, Annabella Sciorra, an actress who has accused Mr. Weinstein of raping her in 1993, to support the predatory sexual assault charge.

Prosecutors won permission to call three other women to testify about the way Mr. Weinstein attacked them to establish a pattern of behavior, even though he was not charged with crimes in those cases.

On Friday, Ms. Mann told the jury she was raped on March 18, 2013, in a room Mr. Weinstein had booked at the Doubletree Hotel on Lexington Avenue in Midtown Manhattan. That morning, she said, she had arranged a breakfast meeting at the hotel with Mr. Weinstein and two of her friends in the film industry.

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On cross-examination, Ms. Mann acknowledged that after the alleged attack, she still went to breakfast with him and her friends. That evening, she said, she attended a movie premiere that he had invited her to. The next day, Ms. Mann acknowledged, she met Mr. Weinstein in the lobby of a hotel.

Prosecutors have tried to portray Ms. Mann as a naïve woman from a dairy farm in Washington State whom Mr. Weinstein took advantage of. But on Monday, Ms. Rotunno used Ms. Mann’s friendly emails to the producer to suggest it was Ms. Mann who was using Mr. Weinstein and attempted to highlight inconsistencies in her testimony.

In one email, Ms. Mann suggested that Mr. Weinstein should meet her mother, adding, “plus you can see how good my genes are.”

About a week after the alleged rape, Ms. Mann emailed Mr. Weinstein’s assistant about a script.

Ms. Rotunno noted that Ms. Mann had continued to send emails to Mr. Weinstein telling him “how wonderful he was,” “thanking him” and “asking him for things.”

She had also given the producer her new number five times over the years. “Every time you sent Harvey Weinstein your new phone number, nobody forced you,” Ms. Rotunno said.

At one point, Ms. Rotunno asked: “You could have walked away from Harvey Weinstein and not ever see him again, correct?”

Ms. Mann responded, “Not from my point of view.”