Jennifer Lopez is already feuding with her new American Idol co-star, host Ryan Seacrest. According to an insider, now that she’s reportedly signed a $12 million deal to be a judge, Jennifer, 41, and Ryan, 35, have begun a power struggle over everything from dressing rooms to which star gets top billing. “Ryan was the one who first suggested Jennifer, but now he’s starting to regret it, because she’s acting like she’s a much bigger star than he is,” the insider says. “Ryan knows the diva behavior is likely to get worse before it gets better. Producers are trying to get them to make peace, but their egos are both pretty big.” J. Lo and fellow Idol newbie, Aerosmith front man Steven Tyler, have created a lot of buzz around a show that many critics say needs a big energy boost. Even fellow celebs are weighing in on the additions. “I’m really excited for Jennifer to be on American Idol,” Fergie recently said.