This is rather bizarre, but I wanted some advice on how to deal

I'm pregnant with my first kid. I wont find out until Monday what the sex is. I have had an overwhelming feeling since I found out I was pregnant that I am carrying a boy. Well, my husbands kid sisters are in town visiting. They have been a complaining mess since their arrival, but that was expected as they complain about everything. Yesterday, we were in a store looking at baby clothes. The youngest of his sisters was looking through baby clothes. She told me, "You better have a girl!" In a very snotty voice. I just said, "I don't want any hurt feelings if I am having a boy." She then told me that she will make me adopt a girl, and if we don't, she will dress my son as a girl and call him "Rochelle." That was the creepy part. Especially since I know she'd try it. I told my husband and his facial expression looked pretty concerned, but he wont say anything. I wont allow it to happen, neither will my husband. They live in another state so its highly unlikely it will ever happen, but I'm a little irritated she would even say something like that. I brushed it off only to make her mad and make her cry a few minutes later. I admit that I was a little hot after that stupid conversation we had and that might have contributed. Really, I just don't know how to deal with this right now. Should I tell my in laws what she said? I know it will upset them. She doesn't leave until Sunday so if she says it again, how do I handle it? Thank you. Sorry if it sounds like I'm mad over nothing.