Are you an ID Addict? If so, Investigation Discovery is serving up a hot new series that examines real-life crimes of passion and the dark side of love. The first episode of Scorned: Love Kills, premiering on Saturday at 10pm ET/PT, introduces us to Joan and David Shannon of Fayetteville, North Carolina. With four kids and a picket fence, you’d never guess that the Shannons were swingers, participating in organized…