The Atomic Kitten star wed former Westlife singer Brian in 2002 and the couple had two daughters together, Molly and Lilly Sue, before separating in 2004. Their divorce was finalised in 2006.
Speaking on ITV's Loose Women today, Kerry said: "It took a long time for me and Brian to become friends. There was a lot of hurt and hatred, especially on my part."
She said now Brian can come round to her house to see the girls and they can exchange texts, but added: "It's not like we are best friends."
Kerry was on the show to give her first TV interview since splitting from third husband, George Kay, in October. They have daughter Dylan-Jorge together. Kerry is also mum to daughter Heidi and son Max from her marriage to Mark Croft.
She told the panel she'd been open with her eldest children, Molly and Lilly, about the separation from George.
"We spoke everything through. They are both highly intelligent girls. I actually do question whether I'm their mum! They have been absolutely amazing. They are just really great kids, as are Max and Heidi. Happy kids who go to school and play outside."
Kerry also credited close friend Katie Price for helping her through this tough time, saying: "Me and Kate have been friends for a very long time and obviously she texts me."
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