There’s a good reason why Britney Spears looked so upbeat and happy on The Late Show with David Letterman on Nov. 6. She’d just signed her petition for divorce, which was filed with the Los Angeles County Superior Court the following day. Spears is citing ‘irreconcilable differences’ as the reason for the split. In her petition, Britney, who turns 25 on Dec. 2, has waived her right to spousal support and requested that the judge order that each party pay their own attorneys’ fees. Britney is also asking for both legal and physical custody of the couple’s children, Sean Preston, 1, and 2-month-old Jayden James, with Kevin, 28, getting visitation rights. The couple became friendly in April 2004 and wed in September later that year after a whirlwind romance. Britney has hired powerhouse celebrity divorce lawyer Laura Wasser, whose client roster includes Angelina Jolie, Nick Lachey and Kiefer Sutherland.