The model was left heartbroken on 7 May when she received confirmation that Kieran had been involved in a sexual relationship with married pal Jane Pountney.
Even more shocking for Katie was the fact Kieran's betrayal was revealed just three days after she announced she's pregnant with his second child.
Initially, it was reported that Katie had allowed Kieran to remain on the grounds of their property so he could be close to their baby son Jett, ten months.
However, according to today's The Sun, the 36-year-old has now asked Kieran to leave their home. A source claims Kieran's mum came to collect him from the house and he's now living with her.
"Kieran has been well and truly shown who is boss in this marriage," said an insider. "He suffered not only the humiliation of being booted out of the marital home with his tail between is legs, but also the demeaning process of his mother having to pick him up."
Kieran's affair was publicly exposed on 7 May when Katie posted a flurry of tweets branding him "disgusting" for cheating on her not long after the birth of their son Jett in August 2013, and continuing to cheat right up until she caught him.
She is six months pregnant with his second child.
The source added to The Sun: "Kieran is a mess and will do anything to save his marriage but Katie won't be made to look the fool. His brain was in his pants and it has cost him dearly."
Kieran was sleeping with Katie's close friend Jane, a married woman who was one of the few guests at Katie and Kieran's wedding in the Bahamas in January 2013.
Katie's sister Sophie was the first person to raise suspicions about Kieran and Jane's closeness, then during a holiday earlier this year, Katie caught Kieran and Jane kissing. At the time Kieran pleaded it was just a drunken kiss and didn't mean anything.
The full truth came out on 7 May.
Shortly after the affair was exposed, Jane publicly admitted she deeply regretted what had happened. Kieran, meanwhile, chose to stay silent until 22 May, when he posted two messages to Katie on Twitter, wishing her a happy 36th birthday and vowing to mend her broken heart.
He then gave two interviews to newspapers where he discussed the details of his affair with Jane and suggested he has "compulsive addiction" and is addicted to lying. A letter he penned to Jane shows him describing their dalliance as just a "dirty, sleazy shag" that had no meaning.
Kieran claimed he was actually glad he'd got caught cheating as he could now seek the help he needed and rebuild his life with Katie. It's reported he's currently undergoing therapy at a £2,500 per day treatment centre.
He's made no secret of the fact he wants to win his wife back, cutting Jane from his life. But Katie has been less than receptive to his advances so far, calling him out on Twitter over the weekend after reading his expose on the affair.
And if it's true she's now kicked him out of the house for good, perhaps this means she really won't take him back.
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