You have every right to be furious. How good a friend is this? If it is someone who in honesty is a work friend then I would probably get the three of them together, make it absolutely plain it goes no further and be very careful what you tell her in future. It's always interesting, a friend told me she was pregnant and to tell nobody. I followed that instruction as given. She met up with my husband and our 2 daughters who are a similar age and made a cryptic comment to my husband about being pregnant (because she obviously assumed I would have told him). He was very, very confused and didn't like to ask her what she was on about. I guess my point is that telling no-one has a different meaning to different people. If I am to be generous I guess they were worried about you and directly asked her what the problem is. I know when I was pregnant last time my boss was really worried about me because I was acting so strangely (early bleeding and sickness) and he was visibly relieved when I told him. The only friend I had told had been interrogated but she lied and said she didn't know what was going on.