Kevin Federline claims in his upcoming memoir that he caught Britney Spears in bed with one of her female backup dancers just a few weeks into their relationship. Federline, 47, writes in You Thought You Knew that he joined Spears, 43, during a night out in Amsterdam in 2004 with her Onyx Hotel Tour crew, including dancer Teresa Espinosa, whom he credits with first introducing the couple at a Hollywood club called Joseph's the month prior.