Who is Paula Mues Beecher from Such a Pretty Girl and what is their importance?

Paula Mues Beecher is a woman with whom Meredith's father had an affair more than 10 years before the beginning of this novel. Although she hadn't realized it at the time, Charles had been molesting her son, Andy. When Mrs. Mues does learn about the abuse, she vows to seek revenge on the man whom she trusted with her son for taking advantage of that trust.