fertilized egg

Im not sure if this is the right place for this. I have an Easter egger that I was told was a pullet, but several weeks later “it” keeps mounting my black silkie hen (only her though!) I’m pretty sure I see saddle feathers coming in but not 100% sure. Anyway, today my black silkie laid an egg...

I have yet ANOTHER broody hen. My adult rooster was killed by a hawk about 1-2 months ago. All I have left are a bunch of 16 week old cockerels that haven't started crowing yet (there have been recent attempts). I've never seen them mount hens, but a younger cockerel that I sold started mounting...

So one of our girls layed some eggs under the house. Here are some pictures one of them. Is this egg fertilized or rotten? We are in Florida so it has been above 95 for some time now.