YTA. OP I think your biggest failing was throwing a baby shower. And then acting super excited about this grandchild on Facebook. It is just so blatantly telling the oldest that you weren't excited for her child but you REALLY love this new grandchild. If you didn't throw the first daughter a shower, you shouldn't have done that for the second, regardless of your health status.

And can you blame the oldest for pointing out that if she had health problems you would've been happy? The way you wrote this, it is pretty clear that you probably would've been happier with a miscarriage for your first. That hurts your oldest. Of course she is upset by that!! Sometimes you don't have to outright say something for people to know it.