JENNA Dewan had no idea that her ex-husband Channing Tatum had moved on until his relationship with Jessie J made headlines, she said.

In the actress' new book, Gracefully You: How to Live Your Best Life Every Day, she revealed that she "felt blindsided' when she learned about Tatum's relationship with the British singer.

Dewan, 38, and Tatum, 39, announced their split in April 2018. In October that year, Tatum and Jessie J entered a high-profile relationship.

"I was learning things about my ex most people wouldn't have to face - and over the internet, as it was happening," Dewan wrote in her book. E! News published an excerpt of the book this week.

In November 2018, Jessie J, 31, took to Instagram to slam commenters that compared her appearance to that of Dewan.

Shortly after, Dewan tweeted her support for Jessie J's statement and said it was a "beautiful message."

Tatum isn't the only one to find happiness after the split, as Dewan is now expecting a child with her boyfriend Steve Kazee.

"When I was ready, I started dating someone amazing," she wrote in her book. "It was this cosmically great thing where we circled back around each other after a moment of instant recognition years ago."

It was also recently announced that Dewan would be hosting a new dating-dance competition hybrid television show called Flirty Dancing. The show will teach partial dance routines to participants, who will then meet their partners to perform the routine in its entirety.

This article originally appeared on Fox News and was reproduced with permission.