I understand that. We asked MIL to tell that side of the family when we had DS. Which she did, all fine. But one of the fuckers then posted it on social media, and tagged me in it, so by the time I was home from hospital and ready to tell certain close friends, then put an announcement up myself, everyone knew already.
What MIL had also been doing, was sharing details about the birth (also difficult and involving medical intervention) with everyone, which also got posted online (as in intimate, personal details which I would NOT have chosen to share with the world). I had no idea she even knew this information, ex DP had told her when he stepped out to call her. I can live with him telling her, he was stressed, worried and seeking reassurance, that I am fine with. Her sharing it with all and sundry, then them putting it on social media I was less than fine with.
We had said in advance we weren't posting pictures on SM at all, yet there were photos posted too, so everyone had also seen photos of DS with me in a state of semi indecency in the background.
I kept them all at arms length in terms of information from that point on. I was furious. When we had DD, MIL was on holiday, so none of them knew she'd been born for 4 days, as we didn't tell her until she got home.
I get how you feel. DS is 9 now, and it still bothers me, and likely still will when he's 23 too.