The pop star, now 41, writes about the pregnancy in her upcoming memoir The Woman in Me: “It was a surprise, but for me, it wasn’t a tragedy. I loved Justin so much. I always expected us to have a family together one day. This would just be much earlier than I’d anticipated. But Justin definitely wasn’t happy about the pregnancy. He scolded me and made me feel like a horrible mother.

She writes in the book: “If it had been left up to me alone, I never would have done it. And yet Justin was so sure that he didn’t want to be a father.”

As Spears describes her experience with the abortion, “To this day, it’s one of the most agonising things I have ever experienced in my life.”

After Spears and Timberlake split in 2002, she gave birth to two kids with her second husband, Kevin Federline: Sean Preston, 18, and Jayden James, 17. On October 24, Spears will publish her much awaited memoir through Gallery Books, a division of Simon & Schuster

The singer’s memoir “illuminates the enduring power of music and love — and the importance of a woman telling her own story, on her own terms,” according to a press release from Gallery Books. It promises to reveal “for the first time her incredible journey (and) strength at the core of one of the greatest performers in pop music history.”