Bittere Wahrheit (1993)

Emma has been happily married to Charles, a hardworking journalist, for over ten years. They have a son, and are considering having another child when she learns that she is both pregnant and HIV-positive at a time when Charles is away. As Emma has never used drugs or slept around, and has never had a blood transfusion, there can only be one source for her infection: her absent husband. Shocked to the core by this turn of events, she goes through his things and finds an address book with the names of many women in it. Determined to discover what has been going on, she begins contacting every name in the book. She continues her investigations even after her husband, whom she confronts over this, returns.