Paris Hilton has had her share of intense relationships, but this one, with Good Charlotte rocker Benji Madden, she swears, is the one. "I am so in love," she told David Letterman last night. "I know I want to spend the rest of my life with Benji. I want to be with him forever. If you saw us together, you'd understand. He's my best friend." It's best friends all around, then, as Paris's other BFF, Nicole Richie, is engaged to Benji's twin, Joel Madden. The question now is, who will make it down the aisle first? An insider confided to In Touch recently that Benji "already told his whole band that he wants Paris to be his wife and have his children." Looks like the race to the chapel is on!