Gwen Stefani and Gavin Rossdale's split may be heading down the road of nastiness, thanks to The Voice judge's estranged hubby hanging out with the previously fired nanny, who was a huge factor in the power-couple's divorce!

An insider revealed to Radar Online, "Gwen is disgusted Gavin is now spending time with the ex-nanny, who also dresses and looks like Gwen. They have been hanging out at Gavin's bachelor pad as he doesn't want to be seen with her in public."

Doesn't the lead singer of Bush realize, everyone ALWAYS finds out?!?

gwen stefani and gavin rossdale

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Prior to the nanny's termination, the blonde beauty was quite close to her children's caretaker. "Gwen loaned her clothes, and was very generous with the younger woman. The nanny was very attractive, but in the beginning, Gwen trusted her and treated her as a younger sister/best friend."

After beginning to feel suspicious of the relationship between the woman and Gavin, Gwen felt she had no choice but to let her go. And now that the father of her children is STILL hanging out with her, we are guessing that it has got to burn!

But the mother-of-three has made it extremely clear when it comes to her precious kids that in the best interests of their well-being, it is best for Gavin to keep the nanny away as "it would be just so confusing for them."

We can't help but agree with her— children first!