For more than a year, the affair between San Francisco Mayor Gavin Newsom and the wife of his good friend and campaign manager, Alex Tourk, was a bomb that those around the mayor knew would one day go off. But it wasn't until last week that the fuse was finally lit, by Tourk's wife herself. After this week's explosion, people close to the mayor, Tourk and Ruby Rippey-Tourk, revealed what had gone on behind the scenes. We're told the affair didn't last long -- the mayor has privately said to friends that there were only a couple of encounters. Rumors...