nearly injured myself in a Airbnb

Hi everyone, I’m from Europe, and I recently booked an Airbnb in the US for myself and some friends. We stayed for 4 days to celebrate a relative’s wedding. Everything was going fine until I was going down the stairs one day, and a step broke off! Luckily, I was able to catch myself and avoid any injury. Upon inspecting the stairs, we noticed that the step that broke didn’t have a support beneath it like the other steps. Another step had clearly been glued back in place but at least had support underneath. We had a relative (who’s somewhat knowledgeable about repairs) come over to look at it, and we all agreed this wasn’t our fault—the missing support was a key factor in why the step broke. I forwarded the pictures to the Airbnb host, and to my surprise, she sent me a $500 invoice for the damages! I’m honestly shocked by the cost, considering how old these stairs are. I’ve reached out to Airbnb for help, and they’ve come back saying I need to pay $260, which I’m still not thrilled about. I’m pretty frustrated because we were very careful to tidy up the house and follow all of the host’s instructions. Now, after very little discussion, she’s hit us with this invoice. My question is: should I be seeking legal counsel for this? How does it work if I’m not from the US? Any advice on how to proceed would be greatly appreciated. Thanks!