Stepmother, The (1972)

aka: Impulsion

Returning home from a business trip, an architect (Alejandro Rey) assumes that a client is having an affair with his wife (Catherine Justice) and murders the man (Mike Kulcsar). His feelings of guilt and attempts to conceal the crime lead to more complications and death. John Anderson, Larry Linville (of M*A*S*H* fame) and Claudia Jennings.