My sister-in-law decided to announce that she will be an Auntie on Facebook without my permission.  Along with her announcement she posted a picture of my baby's ultrasound and then tagged me and my husband in it.  I had not announced it yet to many relatives and long distance friends who have Facebook.  She did not have my permission and had been asked by me in the past to keep it off Facebook because my husband and I had plans to do a post ourselves after we find out the sex.  She did not consult me and instead asked my husband who of course said "sure, that should be ok, it's not like it's a secret I guess" without thinking.  Am I over-reacting by being furious?  Also how can I stop feeling furious?