Los Angeles, June 11 : Pop icon Britney Spears' ex-husband Kevin Federline fears that she's been on crystal meth, he also shared concerns about the mother of his sons overdosing. Kevin, 45, and Britney, 41 - who were married from 2004 until around 2007 - have two sons together: Preston, 17, and Jayden, 16, reports Mirror.co.uk. The former dancer - who has custody of their two children - has shared concern over his ex-wife and reportedly helped stage an intervention in February that didn't go ahead. He said about his ex-wife Britney: "I fear she's on meth - I've been praying someone would make it public and that she wakes up. It's terrifying. She is the mother of my boys." Kevin made the comment to Daphne Barak, as reported by The Sun, and shared with her that he helped set up an intervention in an attempt to 'save Britney from herself'. The outlet states that Britney's sons claim they witnessed someone close to their mother bringing her what looked like drugs before they decided to stop seeing her last year. As per Mirror.co.uk, it's alleged that these concerns, along with what has been described as "erratic behaviour," led to an intervention attempt by people who know her back on February 7. Kevin is said to have been staying with Daphne around then and it's claimed that Britney's friends and family rented a "safe house" in Los Angeles and hired an "interventionist". /IANS