I don't think it can be blamed on you - it was just an unfortunate incident. And I don't think that eating chicken bones is an automatic fiasco... of course we try to keep our dogs away from them because of the risks, but I've known people who fed their dogs chicken bones for years and been lucky enough to never have an issue. Maybe the doggy will be just fine. *hugs*
I hope everything goes well. Take some deep breaths and see if you can let go of some of that guilt.