Katie has spent the day with son Junior and daughter Princess at Madame Tussauds Blackpool and could not resist posing for a picture with their dad.
The former glamour model was married to Australian singer Pete for four years before their bitter split in 2009, and they have only recently begun speaking again.
Clearly having a laugh, Katie posted the photo to Instagram, captioning it: "Reunited."
But while most of her followers saw the funny side, one was not amused. "That is totally unacceptable," the person commented. Oh dear!
Katie is now happily married to husband Kieran Hayler and they have two children together, Bunny and Jett. Pete, meanwhile, is also in wedded bliss with Emily MacDonagh and they are expecting their second child.
Last month, Katie appeared on Loose Women and credited Emily for healing the rift between herself and Peter.
She explained: "With Emily, I think she's really nice. I'm actually glad he's with someone like her. She's a proper lady, she speaks really well, it seems she's come from a lovely family and the kids love her and never say a bad word about her.
"I'd rather he was with someone like her than some gobby person like me."
Katie added: "I have to thank her, because the situation now is that we're all talking. I think it made a difference, him having a woman in his life.
"We now all get on, as Kieran [Hayler] has always been nice to Pete and the kids prefer it."