Am I the Asshole?

Me and my husband are planning my baby first birthday for a while now. My husband have a really large family ( a lot of sibbling ). We choose a date for the event and told people here and there but not everyone was aware yet. (It is still in 5 weeks). Well yesterday one of is brother and his wife invited everyone for a BBQ at there house on the same date. We told them. Hey, we are planning to celebrate babys birthday this day. Its like 2 days before his birthday. Sorry, we did not have the occasion to told you yet. Some people know. Their answer : well we have a busy schedual that month, we can’t move the date. So we are going to keep this date, we hope to see everyone there. ARE YOU KIDDING ME? It’s been 15 years that i am with my husband and I never said a word to his family. But yesterday i dont know if its mom rage or anything but i went off on them. I find its a total disrespect. My husband is afraid of conflict so he avoid it always. Even if it hurts him. Well now I feel kind of guilty because i put my husband in a delicate situation with his brother and his family but at the same time I feel liberated to finally tell how i feel about how they act with us. Mind you, it was all in the family group chat and nobody said a thing. Someone even propose to change the hours of the events so people can go to the 2. I can’t….. its not a freakin wedding, its a BBQ! Am I the asshole?