Thank you guys so much, it's been really nice to have some support all the way thru.
The eggs were pretty clean, some with a bit of poo but they do come out of a butt, after all

I bought several different eggs from several different people and they didn't seem any dirtier than usual?

I agree with you completely that I would never sell a questionable egg, and I have no idea how someone could miss a broody hen if they were being properly vigilant with care. I check my hens at least 3 times a day especially in the heat, which I know isn't entirely possible for some people but like any activity with live animals, you need to devote appropriate time to caring for them. This was irresponsible on her part. No question.
I went back and forth on whether or not I shouldn't or should have assisted and I think I probably would have done an eggtopsy and gotten the same news, so either way I learned some lessons. It sucks to have all this on the first go round of hatching because we were so excited and wanted to do absolutely everything right, and now I'm afraid for the rest of the hatch. But I'm already collecting (MY OWN) eggs for hatching next week. And hopefully I will never have this happen again! Unless you have multiple incubators I would never ever recommend a stacked hatch after this experience. Not that it was intentional, but still will never try it on purpose tho I've seen some people do it.