Did he really need to be informed?

Just looking for some insight here. I have a 6 year old son and I am no longer with his father. I am remarried and my husband and I are expecting a baby in October. We recently told my son he’s going to be a big brother, and of course since he was excited, he told his dad when he went over there for his regular visitation. This was about 2 weeks ago.

Today, I texted my son’s dad to see if I could get my son for a couple hours on a day that would normally be a day with his dad because we are supposed to be finding out what we are having and I would like my son to be able to be there. He agreed, but is now upset that I didn’t inform him I am pregnant. He’s saying I should have told him. I said that 1. My son told me he had already told him and 2. I didn’t really feel it was pertinent. He said “you didn’t feel a major change in my son’s life was pertinent for me to know?”

I’m wondering what other people think. I’m 17 weeks and we literally just started telling people. He certainly wasn’t on the top of my list to notify...I have 23 more weeks to tell him. And I know for a fact he knew because my son told him. But even so, I don’t really feel it’s actually any of his business either way. My son is becoming a big brother. It’s not like this is going to affect when I can have my son or the care my son will get, so is it something I really should have told him? Or am I wrong thinking it’s none of his business?