“My personal life was a bit of a car crash,” Ms. Brooks said.

She told how she met Mr. Kemp in 1995, split up with him, then married him and tried to have a baby, before it all fell apart for good in 2006.

She described the on-and-off intimacy with Mr. Coulson during that time as “quite dysfunctional.”

“It’s probably very easy to blame work, but the hours were very long and hard and you got thrown together in an industry like that,” she said, recalling in particular moving into a hotel close to the office during the time of the Iraq invasion in 2003. “It was wrong, and it shouldn’t have happened but things did.”

At one point, Mr. Laidlaw brought up an unfinished love letter to Mr. Coulson that the police found on Ms. Brooks’s computer. The letter had been read out by the prosecution earlier in the trial as evidence that if Ms. Brooks or Mr. Coulson had known anything about shadowy journalistic practices at The News of the World, they would almost certainly have shared it with the other.

“I tell you everything, I confide in you, I seek your advice, I love you, care about you, worry about you,” Ms. Brooks had written. “In fact without our relationship in my life, I am really not sure how I will cope.”

The letter, she said, was written at a time of “emotional anguish” and after a few drinks. “I do not know if anyone has been in this situation; in a time of hurt, at night after a few glasses of wine, you probably shouldn’t get on your computer,” she said. “But that is obviously what I did. I wrote my feelings down in the moment. These are my thoughts really to myself, but I wrote it in a letter form, probably with the intention of finishing it and sending it, but I probably thought better about it the next day.”

At times, her defense echoed the kind of embarrassing detail and moral failings she and Mr. Coulson once happily splashed across the front pages — some of such articles, prosecutors say, based on hacked voice mail messages.

Ms. Brooks has denied knowledge of the practice or of the name of the private investigator who has admitted to carrying out the hacking while on the payroll of The News of the World. She learned only in 2011, she says, when the newspaper The Guardian broke the news, that the tabloid, under her editorship in 2002, had gained access to the voice mail of an abducted teenager. It was this case above all, of 13-year-old Milly Dowler, who was later found murdered, that caused the storm of public outrage that prompted Mr. Murdoch to close down The News of the World and Ms. Brooks to resign in July 2011.