The mother of John Edwards' young child was cheating on him, Star has discovered. At the same time Rielle Hunter was sleeping with the South Carolina democrat she was also having an affair with Law & Order: Criminal Intent star Jeff Goldblum! Jeff met Rielle in 2006 at the Playhouse West acting school and repertory theater in North Hollywood, where he teaches, we report in our Feb. 22 issue, on newsstands today. "Jeff said he was in love," a source tells Star. "They were extremely close — totally, 100 percent, a major item." When videographer Rielle got pregnant in 2007,...