Glammed up: Kerry Katona heading off to a christening yesterday Kerry Katona has revealed the depth of her drug abuse for the first time in a tell-all interview.The 29-year-old's role as a national sweetheart was eroded by increasingly erratic public behaviour - including her now notorious slurring appearance on This Morning in 2008 - and was finally blown away by pictures being published last year of the mother of four snorting cocaine in her bathroom.Now, having left her husband Mark Croft and dropped from size 14 to size eight, Kerry says she wants to draw a line under the most shameful part of her life.The former Atomic Kitten singer told the News of the World's Fabulous magazine: 'For the first time, I want to talk about everything...