NC for this. Please be gentle with me!
My brother is engaged to my best friend. We're all very close to each other. They've been together a few years and live together. Really happy for them both and make a great couple.
My friend has told me that she's pregnant. Definitely pregnant, not a maybe. Normally I would be really happy. But I very much doubt that my brother is the father because I know he is infertile as this is why his previous marriage broke up.
I honestly don't know what to say to who and when. So I understand there could be some miraculous chance he is actually the father, but that is very very unlikely. I also assumed my brother had told my friend he was infertile, but it seems like he hasn't. And it's entirely possible he has and they have some arrangement I don't know about.
I could say nothing and see what unfolds but I feel like I'm now part of it.