Honestly I feel like I need to make a private comment about someone who has just had a miscarriage.
Why would you do something like that, what kind of comment are you making?
I'm going to make a comment about her future fertility. I need to speak out.
It is hard to have a miscarry and the last thing they need is for people to talk about it. People will think you are a bully for talking about another person's miscarriage.
they have to know how disgusting their actions are
You don't need to tell them any of this at all. They're already suffering because they had a miscarriage. Trust me, doing this will not benefit you at all.