LOS AGNELES: Carrie Underwood has been a bad, bad girl. According to a new report, the former American Idol star has been cheating on husband Mike Fisher with country crooner Brad Paisley. The cheating rumors grew after Carrie, 30, and Brad, 41, sparkled together as hosts of the Nov 6 Country Music Association awards. Carrie and Mike have been struggling to keep their marriage alive following fights over starting a family and fears that Carrie is working so hard she’s headed for a breakdown. “In recent months, as she’s faced one marriage crisis after another, it seems like Carrie is leaning on Brad more than ever,” a source said.–Show