Jenna Dewan felt "blindsided" when she discovered ex Channing Tatum had moved on to date Jessie J, the actress has shared.
Tatum and Dewan, who share six-year-old daughter Everly, announced in April last year that their relationship had come to an end after eight years of marriage. Six months later, 39-year-old Tatum began dating singer Jessie J - with Dewan finding out about the new relationship on the internet.
Dewan, 38, details the discovery in her upcoming book Gracefully You: Finding Beauty and Balance in the Everyday.
In an extract shared by E!, she writes: "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."
Dewan also relates how she drafted tweets to post in response to the news before deleting them and opting to "choose grace".
The mother-of-one shares: "Instead of reacting the way I wanted to (there were many Twitter posts written, then deleted)... I asked myself this: How do I choose grace in this moment?
"Had I not been practicing this way of life beforehand, I definitely wouldn't have handled this news very gracefully."
Dewan has since entered into a relationship with Steve Kazee and is currently expecting the pair's first child together.
In a post to Instagram, Dewan described Kazee as a "gift from above".
Sharing a photo of herself with daughter Everly, she wrote: "Becoming a mother is quite simply the absolute best most incredible thing that has ever happened to me.
"@stevekazee you are a gift from above and i couldn’t be more excited to be expanding our family together...! Thank you guys for all the love!!"
Meanwhile, Tatum deleted his social media profiles earlier in the year to "take a break".
Explaining his decision in a statement before deleting his accounts, he said he hadn't "felt very creative on social in the last couple years now" and was “gonna go and be just in the real world for a while".