Is AUTHOR wrong in the post ? POST : This happened a while back, but I still wonder if I was the asshole. 

I(30M) am a single father of 2 kids. I started a group chat on FB messenger, I named the chat in reference to my kids and included both my parents and siblings(I'm 1 of 6 kids, kinda big family) with the purpose of seeing if someone can watch my kids 2 days during the week the following week. I was also trying to get a head count for 1 of my kids' b-day party that was a few weeks away, too. The whole purpose of the chat was a head count and a sitter for 2 days. My daughter was turning 5, and wanted to make this year memorable.

Now, my brother is a good guy, his wife is a sweetheart, too. He rarely goes on FB and usually turns it off for a few months every couple of months. So we text and talk on the phone more often. 

I start the group, send the message out. He is one of the 1st people to reply. His reply was "wife's grandpa died this morning" and then everyone is giving condolences. 

I knew the guy, nice guy, I felt bad, but I was pissed at my brother. They all seg-wayed and no one was discussing the purpose of the group. I texted him separately and I told him he was being asshole to just announce it to a group created for help with the kids and a head count. He tells me it was just easier to do it to the group.

I got even more pissed.

I tell him he should have started a new group or texted/call us to announce a death, not high-jack the thread about my kids. He says he didn't know the thread was about my kids, like bro, you didn't just see the paragraph 2 comments above yours?

After back and forth, I left the group chat. I called everyone individually to get a head count and see what days they might be able to watch my kids the following week when I worked.

He started a separate group chat and made the announcement again, but we all knew already.

AITA?