Who is Bev Karter from the book, Joy in the Morning?

When Carl's mother cuts off her support, Annie finds a job as a nanny for Bev Karter, a local in the college town. Carl warns against working for this woman but does not prohibit the job because they do need the money. However, after some months, Annie recognizes that Bev Karter sleeps with a married man for monetary support. This scandalizes the innocent young girl and causes her to quit on the spot. Carl consoles his offended wife, who gains valuable worldly knowledge from the affair.