Advice?

So my bil started calling my baby Darius like it's funny like i don't get what's so funny and when he tells people he starts laughing like oh yeah baby Darius and when people started laughing about it I started getting really upset cause it's my baby and no ones gonna be laughing at him without him even being born . I've told them to quit it and he's all no I'll call him what I want now it's like a huge joke with him and the family. Anyways I'm getting fed up to the point where the next person that says that name I'm literally going to cuss them out . Am I being over dramatic or has anyone gone through something similar.. thank you in advance