When news hit that former Republican presidential candidate Herman Cain died of COVID-19 a month after he attended then-President Donald Trump's rally in Tulsa last summer, many of the president's campaign staffers blamed themselves for his death, according to a new book. "We killed Herman Cain," one senior Trump staffer reportedly told ABC News reporter Will Steakin, who also attended the Tulsa event on June 20, 2020. That's according to an excerpt of ABC News' chief Washington correspondent Jonathan Karl's forthcoming book, "Betrayal: The Final Act of the Trump Show," published in Vanity Fair on Thursday. The book is slated...