Katie is currently standing by her cheating husband as he is receiving help for a "sex addiction" and she believes he is already a changed man who is "ashamed" of himself.
Speaking on her Fubar Radio show, the pregnant star said: "Kieran broke every bloody vow. I'm sticking to mine - in sickness and in health - I'm sticking to mine."
Kieran and Katie's best friend, Jane Pountney, have previously apologised for their affair, and Katie has since claimed Kieran confessed to a second affair with another of her friends.
Kieran, who used to work as a part-time stripper, has been seeing a therapist for the past 12 weeks and is working around the clock to conquer his issues.
"In the beginning, the therapist said to Kieran, 'I can't help you if you won't help yourself'. They said he was a compulsive liar - that's how bad it was.
"He's been seeing the therapist for 12 weeks now and has been getting on with his homework. He's a completely different character and person.
"He will need to continue going for therapy for the rest of his life, even if it's once every six months."
Katie added: "I can only try. I'm 36 and am not a kid. I've lived my life and the kids love him so much - they're obsessed.
"We never argue and still don't argue now. If someone came into our house they'd never believe what has gone on.
"We get on so well, that's why I knew it was out of character. What he has done has really shocked his friends and family. We just don't understand it.
"I am old fashioned - if you're in love, no one else should get in the way. I asked him, 'If you loved me that much, why would you do it?' He said he couldn't help himself."
Despite speaking so openly about her marriage troubles, the former glamour model insisted to her radio co-host Mark Dolan that there is "still more to tell".
As a result, Katie is set to reveal all the details of Kieran's cheating in a new book, which will be released next year.
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