Moral dilemma

Tammy Marsh has been a dental hygienist for 10 years and works full time in a general-practice setting. Her best friend`s husband, James Hill, has been a patient of record for the past seven years. Upon updating his medical history at a recent visit, James stated that he was HIV-positive. After the initial shock, Tammy asked James how long he had been aware of his current health status. He told her that he had just been diagnosed HIV-positive within the past month. He also informed the hygienist that his wife was not aware of his condition.
Tammy wonders what should she do? She contemplates telling her best friend about her husbands medical condition.