Britney Spears' memoir, The Woman in Me, will be released next week.

In an exclusive excerpt from the book shared with People, the pop star revealed that she had an abortion during her relationship with fellow singer Justin Timberlake.

"It was a surprise, but not a tragedy for me. I loved Justin very much. I had always hoped that one day we would have a family together. It was just much sooner than I expected," Spears wrote of the pregnancy itself. But Justin wasn't happy about the pregnancy. He said we weren't ready to have a baby yet, that we were too young.

Spears further explained that she did not really want to have an abortion.

"If it had been left to me alone, I never would have done it," she wrote.

"And yet, Justin was convinced he didn't want to be a father.

On abortion, she added, " To this day, it is one of the most painful things I have experienced in my life."

This new revelation prompted a look back at Spears' 2003 music video for "Everytime." Viewers now believe that the song and video were addressing abortion, and the strain it has placed on Spears and Timberlake's relationship.

Spears has since had two sons, Sean Preston (18) and Jayden James (17), with ex-husband Kevin Federline.

Timberlake has two sons, Cyrus (8) and Phineas (2), with his wife Jessica Biel.

The "Toxic" singer and the NSYNC alumnus were in a relationship from 1999 to 2002. At the time of their breakup, they were 20 and 21 years old, respectively.