Losing Chase (1996)

Chase Phillips (Dame Helen Mirren), a lifetime resident of Martha's Vineyard, married Richard (Beau Bridges), and like the area, grew into the upper middle class. Her distaste for artificiality leads her to a wild breakdown, and Richard dutifully tries to restore their family unit as best he knows how by hiring a "Mother's Helper", Elizabeth (Kyra Sedgwick). Chase is broken, and wickedly caustic towards Elizabeth, until they discover each other's similarities. A strong relationship develops, affecting their personal and familial salvation, and destruction.