Mother Love (1989)

A British yuppie couple have a presumably idyllic existence. Yet there is one troubling factor in their lives - an eccentric, and possibly, difficult mother-in-law. Her odd behavior is confirmed in a series of incidents involving her ex-husband, a concert musician, and her ex-husband's new wife, an artist. Flashbacks reveal bits of her troubled past. Little by little, the young couple's life begins to fall apart and the mother-in-law begins to act out her feelings of intense jealousy in the form of revenge, implicating a dear old friend, and leading to murder.