Stefani, 46, toldHarper's Bazaar in a recent interview she is an open book, however, she felt the need to leave out some details considering she has three boys with Rossdale -- Kingston, 10, Zuma, seven, and Apollo, two.
"As a famous person, you start to think, 'I can't say all that because I'll embarrass them or hurt them in some way.' And especially now because they can see everything and hear everything," Stefani told the magazine. "But I've done nothing I'm ashamed of."
After letting out a laugh, Stefani said, "Well, we all have a few things we're ashamed of."
Stefani and Rossdale got married in London in 2002, and according to The Voice star, she found out on February 9, 2015 he had cheated on her with their children's nanny for quite some time. Stefani discovered such horrible news only one day after she performed at the Grammys.
"I obviously know the date," she said, adding that Apollo was "only 11-months-old when everything happened" and "everybody knows what happened."
Stories and rumors then flooded the press, and the world was desperate to find out what went wrong in her seemingly-perfect marriage.
"It was the beginning of hell. Like six, seven, eight months of torture, trying to figure out this big secret," Stefani told Harper's Bazaar. She wanted to "tell everybody," but kept mostly quiet for the sake of her children.
Within no time, Stefani went back to work on The Voice, sought console from friends and began writing songs again. She apparently also coped by praying.
"You know when it gets that bad, you just get desperate? You're on your knees. You're like, 'What do I do?' You can't even go to your parents and ask them what to do," Stefani confessed.
Stefani therefore focused on her kids, whom she only sees part-time now due to her custody arrangement with Rossdale.
"It was so insane because not only did my family break up, but then my kids are taken away like half the time, so that was really like, 'What?! What did I do?'" the No Doubt songstress revealed.
"My dreams were shattered," she continued. "All I wanted my whole life was to have babies, be married, like what my parents have. Then I remember thinking,'There's gotta be a reason for this.' Of course you go through the 'Why me?' and feel sorry for yourself."
But Stefani got back into the studio and recorded No Doubt's Tragic Kingdom. Later on, she released her solo album This Is What the Truth Feels Like, and her first single called "Used to Love You" became a smash hit last October.
"But it was like being handed this gift of a friend who was going through the exact same thing at the exact same time," Stefani admitted.
The couple quickly began dating and went public with their romance right around Halloween last year.
"And then it was just like everything flipped. It went from horrible to, like, hopeful and, like, 'Wow, God, you just don't know what's gonna happen next,'" Stefani noted.
Since then, Stefani confessed that she's had "really bad" days as well as days that are "so good." And as far as her solid relationship with Shelton goes, she gushed, "It's crazy the support and love I've felt. Life is such a weird... I mean, I can't believe I'm number one on a country chart."
Stefani was referring to the duet she recently recorded with Shelton called "Go Ahead and Break My Heart." The pair performed it together for the first time on The Voice's tenth season.