Article continues below advertisementRosie O'Donnell looked back at her former friendship with Ellen DeGeneres and called their falling out one of the most difficult things she's experienced in show business. O'Donnell, 63, explained the end of their friendly relationship during the Sunday, September 7, episode of the "No Filter" podcast, recalling how DeGeneres, 67, announced that they weren't friends during a 2004 interview on Larry King Live.