Not that this came as any surprise, but here's the skinny on it...From the National Enquirer:
Nicole Richie and Paris Hilton are enemies once again. The on-again, off-again BFFs have had a huge blowup over Paris’ abrupt dumping of Benji Madden — the brother of Nicole’s boyfriend Joel, say sources. And to make matters worse, the hotel hottie has apparently already moved on. Paris hooked up with mega-wealthy high-end jeweler Pascal Mouawad at the Nov. 15 Victoria’s Secret Fashion Show in Miami, where she modeled his one-of-a-kind, 130-carat diamond necklace worth $3 million.
“Nicole feels that Paris never really liked Benji, but used the relationship to get more publicity for herself,” charged the source. “She saw the opportunity and jumped on it . . . Paris will be Paris — she does only what’s best for her.”