Deception: A Mother's Secret (1991)

Terry is married to Amanda and he wants to adopt his stepson Jay. When Amanda dies in a car accident, Terry begins working on trying to adopt Jay so that he won't be sent to a foster home. He discovers that not only is Amanda's ex-husband not Jay's father, but that she was infertile. So where did Jay come from? Terry is not sure if he wants to find out, because it means that he might lose Jay.