The tenant won't give you answers. She's gone. She doesn't want to face responsibility, either because she's embarrassed after really doing the best she could and just not being able to make it, or because she could be one of those "professional tenants". You'll likely never know.

You know yourself and after this, you know whether you have the stomach and resolve to be tough or to balance that toughness with compassion where needed. If you don't, it might be worth considering engaging a property management company, because really, you don't want to light bags of dogshit on fire. :)