Gwen Stefani appeared to say she used to love ex-husband Gavin Rossdale in her new song "Used To Love You," and it became clear Wednesday what made her want to walk away from their marriage: The singer discovered Rossdale was cheating on her with the woman who would watch the couple's children, according to reports.

Us Weekly reported that the couple's 13-year marriage came to a close because of Rossdale having a three-year relationship with their nanny, Mindy Mann. She cared for the couple's three children: Kingston, 9, Zuma, 7, and Apollo, 1. Stefani allegedly discovered the affair in February.

In an interview with KIIS FM's JoJo Wright Monday, Stefani hinted that everything changed that month. "Everybody knows that my life blew up last February. I'd just been dealing with that. Unexpected. I was going along thinking that was going to be the rest of my life, and it's not. I don't know what happened," she dished.

Stefani allegedly discovered the Bush frontman was cheating when she found "explicit" texts from Mann to Rossdale on the family's iPad because his phone was linked to it. The No Doubt singer is reported to have found nude pictures of Mann and plans for Rossdale and her to meet up. 

The couple filed for divorce in August and intended to keep their three sons as comfortable as possible throughout the process. In a statement to E Online, they said, "While the two of us have come to the mutual decision that we will no longer be partners in marriage, we remain partners in parenthood and are committed to jointly raising our three sons in a happy and healthy environment."

After the divorce that was finalized last month, Stefani has appeared to move on with a fellow coach on "The Voice," Blake Shelton, who also went through a divorce this year. News broke that the two were a couple before the 2015 Country Music Association Awards presentation Nov. 4, but Stefani denied the rumors she was in a relationship with Shelton on the "Frankie and Geena Morning Show" on KHTS-FM radio in El Cajon, California, as reported by TMZ.

"This is what I'll say about that: I never said nothing about being in a new relationship. I don't know who said that, but somebody did and then my kid came in last night to tell me about it, so that's how crazy my life is. People just can say whatever they want and then they can just believe it," she dished. 

Entertainment Tonight said Shelton's representative confirmed they were a couple last week. The two taped their first episode of "The Voice" as a supposed couple Tuesday, and it was reported the two shared some loving moments when the cameras weren't rolling. Shelton is set to host the 29th annual Kids Choice Awards show in March, and he extended an invitation to Stefani and her sons.

"If she wants to bring the boys out there, that's awesome!" Shelton told Entertainment Tonight.