Sex wasn’t just a pleasurable pastime for jailed singer R. Kelly, it was the shamed former superstar’s preferred “weapon” of choice, according to Reshona Landfair.  The 41-year-old mother of one, and author of the new memoir “Who Was Watching Shorty: Reclaiming Myself from the Shame of R. Kelly’s Abuse,” out now, is coming forward as the 14-year-old girl featured in the disgraced R&B singer’s graphic video. The foul footage, filmed in the late 1990s, shows R. Kelly, née Robert Sylvester Kelly,