JEFFERSON CITY, Mo. — In his first interview since acknowledging an extramarital affair, Missouri Gov. Eric Greitens said Saturday that there was “no blackmail” and “no threat of violence” by him in what he described as a months-long “consensual relationship” with his former hairdresser. Greitens said he has no plans to resign from office as a result of the affair, despite calls to step aside from several Republican and Democratic state lawmakers. “I’m staying.