Actress and dancer Jenna Dewan has revealed she felt "blindsided" when she found out about her ex-husband Channing Tatumn's new relationship with singer Jessie J at the same time as the rest of the world.

In her upcoming book Gracefully You: How to Live Your Best Life Every Day, the Step Up star said she found the situation "really difficult".

In an excerpt published by E!, she wrote: "I was learning things about my ex most people wouldn't have to face - and over the internet, as it was happening.

"There I was, on a plane, alone, finding out about his new relationship. I felt blindsided. Choosing grace as I learned everything about my personal situation along with the rest of the world was really difficult."

Jenna Dewan writes about finding out about ex Channing Tatum's new romance with Jessie J

Dewan and Tatum announced that they were separating after nine years of marriage in April 2018.

The actress opened up about coming to terms with their divorce in her new book.

"[Divorce] was never on my docket of dreams, but alas, here I am, learning and growing through one," she wrote.

"In the beginning I turned to the typical remedies. I drank a whole lot of wine with friends. I had many moments of deep, painful, big cries. And both were very necessary in getting me to the next hour, through the day, on to another week."

Jenna Dewan said she was in "a state of shock" after separation from husband Channing Tatum

She revealed that the press coverage of the split left her reeling.

"In the beginning of my separation, it felt as though I were in a dark closet, desperately trying to find the light or the way out," she wrote. "I was in a state of shock. One week I'd be doing really well and the next I was slammed with a whole new slew of emotions.

"The rumor mill was churning out story after story. There were many times I hid under the covers, wondering what was next. The pain hit me like a tumbling avalanche. I was completely overcome with fear and sadness.

"It took many moments of sitting alone with my grief to force me into surrendering to my roller coaster of a situation."

Dewan is now in a relationship with Steve Kazee and the couple are expecting their first child together.

She wrote of meeting Kazee: "When I was ready, I started dating someone amazing.

"It was this cosmically great thing where we circled back around each other after a moment of instant recognition years ago."

Dewan is already parent to six-year-old daughter Everly with Tatum.