Feeling left out of family celebrations

Can I get some advice Alikes? My sister in law is coming to town for her sons birthday. I’m excited to see her and celebrate my nephews birthday but there’s this nagging thought in my head. I have a four year old and in February I invited everyone from my family and my husbands family to be a part of it. No one came to celebrate and some of them didn’t even respond. I didn’t expect much from my family but I guess I expected something from my husbands. And now everyone’s rallying behind my sister in law for her sons birthday. Making cupcakes and buying gifts and planning themes and invitations. My inlaws don’t like me that’s a known fact but I thought they would be their for the grandchild. They’ve made it obvious which grandchild is their favorite but I thought they’d make an effort to at least act like they’re equal. Am I angry for no reason? Should I just get over it? I can’t bring it up and make my already strained relationship with my in-laws worse. What should I do?