There's a certain kind of madness that comes with loving a creature that wants absolutely nothing to do with you. This hen blew in with a storm, stayed for the free grub, and has now decided that a hollow tree is the penthouse suite of her dreams. I get it. You built her a perfectly good nesting box, and she looked at it like it owed her money. Instead, she chose a spot that requires a search party and a pair of thick gloves just to check on her. That's not ingratitude. That's just chicken logic, and honestly? It's kind of endearing.
Here's the thing about the eggs, and I say this with all the warmth I can muster: they're duds. Without a rooster, those eggs are never going to hatch, no matter how long she sits on them. And she will sit. She'll sit until she's a skeleton with feathers, waiting for a miracle that's not coming. The practical move is to break her of this broodiness now, because a hen that's determined to hatch nothing will stop eating, drinking, and moving. She'll waste away on that nest, and you'll be left feeling like the villain who didn't save her from herself. You don't want that. She's already pecked at you when you tried to pet her, which is her way of saying, "Back off, I'm busy being miserable."
But here's where your trust matters more than your guilt. You can't just yank her off the nest and call it a day, because she'll just go right back. You've got to block off that tree hollow, or at least make it impossible for her to return to the exact spot. Then you've got to lock her in a safe, bare space for a few days, like a dog crate or a wire pen with food and water. She'll throw a fit, probably scream bloody murder, but she'll snap out of it. She'll realize the eggs are gone, and her hormones will take a nosedive. Then you can give her that nice box you bought, and she might actually use it. Or she won't, because she's a chicken, and she'll find a new way to stress you out.
The real lesson here, and I say this because we've all been there, is that you can't save a stray by giving them what you think they need. You save them by giving them what they actually need, even when they fight you for it. You've already done the hard part, you kept her alive through the storms and the owl scares. Now you've got to be the bad guy for three days so she can live a long, boring, egg-laying life. She might not thank you for it. She might peck you again. But that's fine, because you'll know you did right by her, and that's a cluck-tastic feeling, even if it comes with a few scratches.