Ben Affleck and Jen Lopez are back together ... at least for one night only ... but it's strictly business. The famous exes reunited Monday for a movie premiere in New York City ... showing up for the first screening of "Kiss of the Spider Woman." Jen stars in the musical and Ben serves as an executive producer. Artist Equity, the production company he shares with Matt Damon , helped produce the flick. Ben and Jen mugged for the cameras, standing shoulder to shoulder ... and he even wrapped his