Photo: Nino Muñoz

But just two months into their relationship in 2007, they discovered that his ex-girlfriend,Bridget Moynahan, was pregnant with his first child: son John “Jack” Edward Thomas, now 11.
“It wasn’t the ideal situation for anyone — there’s no manual to prepare you for that,” Bündchen tells PEOPLE in a revealing new interview for this week’s issue.
“But I’m so grateful for [Bridget],” she says. “I know this was hard, but I couldn’t imagine my life without [Jack]. I call him my bonus child.”
After Jack was born, “He opened my heart in ways I didn’t even know my heart could expand,” says the supermodel andLessons: My Path to a Meaningful Lifeauthor,38. “I fell in love with him.”
She says feeling such love for her husband’s son made her “want to start a family” with Brady, whom she married in 2009. And though they had previously discussed waiting 10 years to have children, they realized they “wanted Jack to have a brother or sister close in age.”
Gisele Bundchen/Instagram

Nino Muñoz

In her new memoir —Lessons: My Path to a Meaningful Life,written in the style of a journal — the famously private supermodel reveals that motherhood was a tough adjustment. (She and Brady, 41, share daughterVivian Lake, 5½, and sonBenjamin Rein, 8½.)
“Things can be looking perfect on the outside, but you have no idea what’s really going on,” Bündchen tells PEOPLE. “I felt like maybe it was time toshare some of my vulnerabilities, and it made me realize, everything I’ve lived through, I would never change, because I think I am who I am because of those experiences.”
“When I became a mom, I kind of lost myself. It was like a part of me died,” she adds. “I’d been this very independent person. It was all about me. But now I had this little being, and I suddenly felt l couldn’t do other things and that was very hard for me. All I ever wanted was to be a mom, butwhen you’re actually experiencing that, it’s a shock.”
Peter Zambouros

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Bündchen also acknowledges that the stresses of parenting have sometimes taken a toll on her marriage. Taking on the majority of the childcare while Brady trains — often from 6 a.m. to 6 p.m. — “You’reoverwhelmed and tired and thenyou’re not the nicest partner,” she admits.
“When someone you love is happy, it makes you happy, or if they’re sad it makes you sad,” she says. “You suffer with them and you have joy with them.”
All proceeds from Bündchen’s book will go toProjeto Agua Limpa.
For more about Gisele Bündchen’s new book and life at home as a mom and stepmom, pick up the latest issue ofPEOPLE, on newsstands Friday.
source: people.com