KEVIN FEDERLINE is convinced his controversial and headline-grabbing marriage to Britney Spears is a stepping stone to superstardom. Despite a bitter divorce and an ongoing custody battle, all played out under the watchful gaze of the world's media, Federline has no regrets about his disastrous relationship with the singer. Instead, he plans to use it to make him a bigger star than Spears herself. He tells Interview magazine, "I never will regret anything that's ever happened in my life. I look at life as a lesson. I am a very strong believer that this is a stepping-stone for something else. Not to say I like having the paparazzi around or that I like having my life in the media. But as much as I try to be mad at it, I can't be. "The paparazzi and the press have given me a voice. One day I'll be able to use that voice."