Gavin Rossdale and Gwen Stefani's split just got a whole lot more scandalous!

According to a new report, the 46-year-old blonde beauty ended her 13-year marriage after discovering that her rocker hubby was having an affair with the family's longtime nanny, Mindy Mann.

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A source says the duo's intimate relationship had been going on for three years, including during the time that Gwen was pregnant with her third child, Apollo, 20 months.

gwen stefani

Gwen and Gavin with their three boys in June.

The Voice coach allegedly found out about the affair when another nanny discovered explicit texts and nude photos of Mann on the family's iPad.

“The iPad was linked to Gavin’s phone,” a family source tells Us Weekly. But at the time, Gavin, 50, reportedly claimed that the exchanges were simply "flirtations" and nothing more. The insider says he later confessed to adultery months later.

RELATED: Gavin Rossdale Steps Out Wearing Wedding Ring After Gwen Stefani Admits She's Dating Blake Shelton

“[It] completely devastated her,” another source tells the mag. “She was mortified, livid, and embarrassed. This was done right under Gwen’s nose."

Scroll down for more celebs who've had affairs with their children's caretakers!