MIL is pissing me off

My mother in law wants a granddaughter so bad...she has two grandsons already and a girl hasn't  been born in my Dh side of the family for almost 15 years...so I understand why she wants a granddaughter so bad...but when we found out that my son was a boy the first thing she said was "damnit..I wanted a granddaughter!" And then proceeded to ask the ultrasound tech 4 times if she was sure it was a boy and to check again.....it pissed me off and killed the excitement for my husband and I. This time I'm not having anyone in the room except my husband and I. Especially since she's already saying dumb stuff about "it better be a girl or she's gonna be upset"