The former glamour model separated from Peter in 2009 after nearly four years of marriage and two children: Junior, three, and Princess, who was nearly two.
On today's ITV's Loose Women, the panel discussed a new report that claimed kids whose parents are still married will flourish more than those whose parents have split.
"I think people forget about us parents," said Katie, 37. "When I split with Pete it killed me because I had to agree he had the kids half and half. From being with me all the time to having to split them. I did it for the kids' sake but I'll never forgive that situation that I was forced to do it."
When it was pointed out Pete has a right to see the kids as well, she replied: "I didn't want to divorce him. I wanted to be with him."
Katie said she and Pete, 43, had never sat down with the kids or each other to talk about why the divorce happened. When asked if she felt talking would have rectified the problem, she replied: "We would have stayed together, I genuinely believe that."
But she added: "It doesn't matter now. I'm happily married. And even when I've said to Junior and Princess, 'would you like me and your dad to be together?' Princess is like, 'No, I love [Katie's husband] Kieran and [Pete's wife] Emily' so they're quite happy. And I know they get love from him and they get love from us."
Katie is married to third husband Kieran Hayler, the father of her youngest children Bunny and Jett. She's also mum to teenage son Harvey from her relationship with ex Dwight Yorke. Peter, meanwhile, is married to doctor Emily, the mother of his young daughter Amelia.