It was a dramatic move from Pete after refusing to speak to his ex-wife, or even look at her, for the past six months.
But Pete, 36, couldn't contain his anger any longer when he saw Alex on Celebrity Big Brother, according to Now's well-placed source.
The insider says: 'He hates Alex being near the children and when they came to visit for a couple of nights last Monday, Junior was saying: "Daddy, daddy, I want to watch Alex."
'Pete couldn't believe it. He feels that Katie's been urging the kids to watch CBB. He was so incensed he called Katie, which he'd never usually do. He even had to ask his brother Mike for her number.
'He was upset and said: "It's my time with the kids, so why are they asking about Alex?" But she was just as annoyed as he was and told him she was sick of friends and family asking her about Alex.
'Jordan loves the limelight, so she's never thrilled about sharing attention with Alex. But she was left wondering why Pete had got in such a tizz about it.'
She's not the only one. Friends say they've never seen Pete so jealous, with some questioning why he's getting so worked up if he doesn't have feelings for Jordan.
'It doesn't make sense unless he still cares about her, but won't admit it to himself,' adds our source.
'Pete's harboured a grudge against Alex ever since he stopped Pete speaking to the children on the phone in a bust-up last August. His behaviour is the first sign that all is not well in his camp.
'In the last two weeks, he's kept a low profile after visiting his parents in Australia.'
Mysteriously, although he's This Morning's showbiz reporter, he didn't go to the National Television Awards last week. 'He lives in fear of bumping into Jordan, who did go,' says our source. 'It overtakes his life at times.'
But this week, Pete embarks on a promotional drive for his new album Unconditional Love Songs, released on 1 February, his tour, which begins on 19 February, and new biography My Story, released on 1 March.
Although his tour's a sellout, Pete still fears that his career will go pear-shaped, especially now that he's lost his most marketable asset - Jordan.
He admitted last week that he'd started watching CBB, so he's spent the week having to witness Alex's star rise as the next Mr Jordan.
Now Alex has popularity on his side after coming across well on the show, it's a sting for Pete.
Another source tells Now: 'Pete's always been racked with self-doubt. He's petrified of it all going wrong and of having another breakdown.
'It's tough on Pete when he's out of the limelight, because it crumbles his confidence, which is fragile at the best of times.
'It's especially hard to see Alex doing so well on CBB.
'All those who know him well can see the cracks appearing and he's now wanting to do more things to get noticed as his music career hasn't been quite what he hoped for.'
To add to his worries that he's still not fully established as a genuine music talent, it seems his ex-wife is falling back in love with Alex.
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