She-Devil (1989)

Ruth is a wife and mother who tries to please her husband (Bob) but finds him pulling away and spending more time at the office than at home. When he begins an affair with a famous romance novelist (Mary) and leaves Ruth to raise their kids, she decides she's had enough of playing nice docile housewife. Ruth endeavors to show Bob and Mary the truth about themselves and each other, while creating a new successful life of her own.