I can't be the only one who doesn't want my ex knowing my business?

I'm 21 weeks, and have been broken up from the ex about four years , remarried one year. just two days ago told I my six year old son that I share with my ex that he'll be getting a sister. The seventeen year old son we also share has known for longer. He's much more mature than his brother (obviously! Lol), has a concept of time, and can understand that medical information is something that people often wish to keep private. I did ask him to not share with the ex yet.

The boys are with the ex this weekend, and the little one (unsurprisingly) said something about how he's getting a sister. That's fine, it's exciting for him! I knew that as soon as he knew, ex would find out. This did factor into my decision of how early to tell him.

What annoys the crap out of me is, of course, the ex got all butt hurt. Went off on the teenager, then on me about how kids should never be required to keep secrets from a parent.

Hello, it's NOT all about you! Yes I asked the nearly adult child to keep my medical info private. However, the little one has known for a day and a half, and was given NO instructions, just good news. I didn't expect any secrecy from him! Just because your parents made you keep their sexual affairs and infidelities secret from each other doesn't make my life and my choices about you!

Ugh. Exes are exes for a reason, and I'm SO grateful for my current partner!