I'm so sorry @Sandra245, it is of course upsetting to have damage to your house, and from what you've written here it sounds like you are very house proud.
As a host I want my guests to treat my place(s) with respect, and if they damage something, to let me know so that we can figure things out. As a guest, I want to have a great stay, and I want to not have accusations that I damaged something. So where do you find a good middle ground? In this case, you have no hard proof that these particular guests caused this damage. You can make some deductions (you didn't notice it after last guests) but unless you have physical proof, you're stuck.
It's two pages back and I read it quickly, but it sounds like your first impression was that these were good & responsible guests? If that's correct, can you live with giving them the benefit of the doubt and undertake the expensive repairs on your own?
It sounds like the situation has escalated to a point where you now can't really backtrack. You'll have to figure out where you go from here. I can only share my experiences. I've had damages in my places and where I can't totally prove it was as a result of a guest, I fix it. If I had damage done on camera, if I absolutely knew with pictures of before and after - maybe then I'd push it through the resolution system.
The only time that I've ever asked for guest damages is after smoking in my apartment where I SAW them smoking and Airbnb still denied the claim....
Best of luck to you with your situation!