The 35-year-old's message to Kieran was published in a July 2013 interview – less than a year before she announced they were divorcing following allegations Kieran had been unfaithful.
In the interview with The New Review, model Katie said past experience had made her decide Kieran would not benefit from her rumoured £45 million fortune in the event of a split.
"It's a shame, in a way, because he is lovely, and I want to spoil him, but I've said to him that I've been taken advantage of so bad in the past that unfortunately he's going to get f**k all from me.
"It's what will keep us together."
Many were left stunned this week when Katie announced her plans to divorce Kieran, shortly after they celebrated their first wedding anniversary.
The model sent a flurry of tweets accusing Kieran of having a seven-month sexual affair with her friend Jane Pountney, branding him "disgusting".
Making the situation more shocking for fans was the fact just three days earlier Katie had happily announced she's pregnant with Kieran's second child.
The couple already have son Jett, who is nearly one.
In a statement confirming their split, Katie said: "I appreciate most people will have seen my tweets on the subject of my marriage to Kieran.
"I make no apologies for them though it will be appreciated that, sending them immediately after Kieran confirmed to me what he had been doing for the last 7 months, those tweets were a sign of my heart breaking."
She added: "That he was doing it with a close friend of nearly 20 years is hard to understand."
Kieran has not yet responded to Katie or the allegations, although he was seen alongside Katie at Jane Pountney's home after the news broke.
Jane has also kept quiet although her husband Derrick has branded the reports of the alleged affair as "exaggerated" and a "storm in a teacup".
"There's a lot of misunderstandings to sort out," he said. "Now Katie has gone and put the whole thing for everyone to read about on Twitter, which she didn't really need to do, and a drunk kiss has turned into a full-on affair."
Earlier today, it was claimed that Katie has asked Kieran to move out of their shared West Sussex house and into a cabin in the garden while she thinks about what she wants to do next.
Katie and Kieran married in January 2013 in the Bahamas following a whirlwind romance and Christmas proposal. Their son Jett arrived that summer. Katie is also mum to kids Harvey, Junior and Princess from past relationships.
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Katie's ex-boyfriends in pictures:
Copyright: PA Images