Family boundaries

Hi, I got mad at my sister in law today for wanting to impose a nickname on my baby, THAT HASNT EVEN BEEN BORN YET, I calmly tried to walk away from the conversation but she keep talking about all the ways she will call my baby (he already has a name) and that I couldn’t control what other people wanted to do and she proceeded to mention if I was going to be a helicopter mom, needless to say that made me furious since I am the one who is pregnant not her, why is she making decisions for me or my baby??? I feel like I am acting crazy, it’s not the nickname that I care is the fact of trying to impose your opinions over mine