My boyfriend doesn’t understand

My boyfriends sister doesn’t like my son. He is only 7 weeks old and she does not even acknowledge him. She’ll baby talk to her other two nephews and hold them and take care of them. But my boyfriend will literally have to tell her to even say hi to him. Example “hey don’t forget about Declan.” It’s one thing to not like me but to not like an innocent baby is completely uncalled for. Not to mention she literally said “this sucks, another boy” when we revealed the gender to his family and missed his baby shower

My boyfriend doesn’t understand why it hurts me so much and why I don’t even want to bring him around her