SACRAMENTO, Calif. — Keith Papini, who loyally stood by his wife’s side for six years as Sherri Papini maintained she had been kidnapped, filed for divorce Wednesday, two days after she pleaded guilty to charges that the whole thing was a hoax. Online records in Shasta County Superior Court say Keith Papini filed for “dissolution with minor children” on Wednesday and that a hearing is set for May 9. Sherri Papini’s attorney, William Portanova, who was with her when she pleaded guilty Monday in federal court to lying to the FBI and mail fraud, declined to comment Friday. Keith Papini appeared t…