Am I wrong or is he?

I have been planning Easter since February. I invited my family and my husband's family. I planned this event for the kids mainly! Now... About 4 days ago my husband's mother calls him inviting him to his grandpa's for a cook out even though I invited her to ours and she cancelled.

The only person showing up out of the 15 people I invited was my sister and her kids. Now my sister won't be able to make it until around 3 and my husband's grandpa is having his at 3 he lives about an hour away and my husband wants to leave take our son with us so he can go to his grandpa for their cook out... I told him "I have been planning this for almost 3 months and you've only known about your grandpa's cook out for 5 days. now all of a sudden my party that I'm throwing which I invited your family to takes a back burner because your grandpa is grilling out?

I'm grilling out too and the real only reason I think he wants to go is to show his grandpa how successful he is compared to the rest of the family.

(I think it's a lame excuse to go there)

So am I wrong for being like this or is he wrong?

He says it's because his grandpa is getting up there in years and he doesn't know how many more times he'll be able to do this.