Who is Laura Barney from 'I' Is for Innocent and what is their importance?

Laura and David Barney were married for three years. She came with David to Santa Theresa from Los Angeles when he took a job with an architecture firm there. Laura encouraged her husband to befriend Isabelle because she was the architect's pet. When she later learned that the two were having an affair, she confronted him, forcing him into a divorce and marriage to Isabelle.