Patient confidentiality VS Patient safety

You are a GP who is currently seeing a husband (Mr Williams) and wife( Mrs Williams). You see them on separate occasions as they sometimes want to keep their medical history separate. Mr Williams recently went on a overseas trip and confessed to sleeping with a prostitute while away. His tests for HIV have come back positive. He does not want you to tell his wife yet, as he wants to tell her himself. The very next day Mrs Williams comes to visit you and complains of feeling very unwell. You test her first before making any decisions and her tests come back positive for HIV. With your knowledge of what Mr Williams has done, or do you break patient confidentiality and tell her.