I just need to vent.

I’m currently off work and I’m trying to bend my baby shower to work with everybody. I was able to have it at a relatives house but they live about 45 mins away from my so and I and his side of the family and his family said that was too far of a drive. I can’t afford to rent a hall so his sister said we can throw it at her place as ours is really small and in the middle of Reno’s. I put down a couple weekends of different dates and let them all decide which one works best, and they did. Today they messaged me and asked to move my hours and shorten it so they could go to a festival... am I wrong for being a tad upset? All of the people attending are coming from out of town, the date and time were already given to them... and they are already going out of their way to come where we’re having it. I’ve done everything for his side of the family, I’ve been there and helped with EVERYTHING... and now I’m just supposed to change the shower times because they want to attend a festival? It’s just a bit over whelming and when I said I don’t think it’s going to work to change the times... they got a bit mad? They had the option to choose a different date... so why wouldn’t they? I don’t get it