The 32-year-old star - who is currently dating Argentinean model Leandro Penna - has been married twice, to Peter Andre and Alex Reid, and has three kids from previous relationships but says former Another Level singer Dane was her one true love until he broke her heart.
She said: "I've been hurt before. I've been heartbroken badly, when I split from Dane. He was the only guy who completely taught me about having your heart broken.
"I've always said that Dane's the one who did that. Because of Dane, he's made me have my barriers up and even with Pete, I'd like to say they all went down but there were a couple up still.
"Since splitting with Dane I have never let my barriers 100 per cent down with anyone. Being heartbroken, that hurt. It's not a nice feeling."
Katie and Alex split in January after less than a year of marriage but she now regrets the relationship calling it a "rebound" after she and Peter broke up.
Speaking on her reality TV show 'Katie', she said: "With Alex, if things were resolvable then they would have been resolved but it was an impossible task. It would never have worked. He was a rebound."
Although Katie and Leandro, 25, have only been dating since February and struggle to communicate because of a language barrier, the former glamour model is completely smitten with him.
She said: "I know it's quick and it's not what I wanted but it feels right. There's a language barrier but the chemistry overtakes it."