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The TV presenter, 38, was comforted by Matt as she explained to Fearne Cotton her decision to stand by the musician and help him overcome his problems.
"He went to rehab when I'd known him for three months. We hadn't known each other for very long and I was kind of in this whirlwind with him," said Emma, who has been married to Matt since 2008 and has two children with him, Isabelle, four, and Ace, two.
"You don't really think about it, then more time goes along and he went in again."
Trying hard not to cry, she added, "This isn't a kid that needs a couple of weeks break, it's someone who genuinely has a problem.
"I'm not going to leave him because he has a problem. You stick together and get through it."
Happily Matt, 31, is now clean and sober. "He's very boring," his proud wife joked. "I'll take boring over the alternative.
"I'll take the tattoos and the motorbikes over all the other stuff."
Matt was first admitted to The Priory in 2005 for alcohol abuse, and re-entered in 2006 for an addiction to cannabis.
In the new fly-on-the-wall documentary, Fearne chats to friends and family of the McBusted boys in a series of revealing interviews. It will see her delve into their pasts as well as following the band as they prepare for their UK tour.
Fearne and McBusted airs on ITV2, starting on 21 May.