In the wake of the revelation that an FBI informant lured George Papadopoulos to London during the 2016 campaign, the former Trump campaign adviser has grown skeptical of many of his contacts during and after the election, his wife says. Papadopoulos’ contacts with the FBI informant — a former University of Cambridge professor named Stefan Halper — have been widely reported over the past several weeks. The 30-year-old Chicago native’s interactions with Joseph Mifsud and Alexander Downer, two diplomats who are key to special counsel Robert Mueller’s investigation into Russian meddling in the election, are also well known. Simona Mangiante,...