Nicole, 38, was on holiday with her family when reports came out that a mystery rock star had been involved in a lovechild scandal.
Nicole and her sister Natalie were having their hair done and light-heartedly guessing who the man in question was when the All Saints singer received a phone call from Liam, according to reports by The Mirror.
"It's Liam, it's Liam!" Nicole is reported to have cried when the former Oasis front man confessed his infidelity. Liam rang to warn her a day before his name was revealed in the papers.
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"Nikki's devastated — we all are," said Mary. "She said to me, 'Mum, he hasn't even called to ask how the boys are."
Liam and Nicole have one child together, twelve-year old son Gene, but Liam's other son Lennon, 13, from his first marriage to Patsy Kensit, was also on holiday Nicole and her three sisters Lori, Lee and Natalie.
Nicole is reportedly being comforted by her older sisters, and is not ready to face Liam. The couple were meant to spend the rest of the holiday together after Liam finishes performing with his band Beady Eye in Spain.
Nicole has reportedly kicked the musician out of their marital home and is said to be furious. She has not made any comments on her Twitter account, while Liam's spokesman has dismissed the scandal as gossip.
Liam has been accused of fathering a love child with journalist Liza Ghorbani who is suing the rock star for $3million (£1.9million) worth of paternity costs.
According to the New York Post, Liza gave birth to a little girl named Emma seven months ago after a long-running affair. The newspaper also stated that Liam has "admitted the child is his in an email, saying she is a beautiful child because she has his 'rock star genes.'"
The relationship allegedly started after Liza wrote an article for the New York Times entitled A Night Out With Liam Gallagher in May 2010. Their fling reportedly finished after Emma was born.
"Liza met Liam when she interviewed him for the Times, and they began an affair," a source told the publication. "It continued until around three months after the birth of the child. He ended the relationship when she told him she was suing him for child support."
Liam's spokespeople have confirmed that the singer is taking legal action against the New York Post.