In the Kitchen then feed the dog on the sly another thing you could do is tell your neighbor is somebody wants to give you a dog house cause their dog is too big or whatever but since you dont need it would she like it for her outside dog if she say yes find a dog house.In times like this I have no problem telling a lie.
I could tell you stories but you dont need to hear it and if you can make this creature be a little more comfortable it will make you feel alot better.Just dont ever let her think you think she is not treating the dog right cause then she will get really stubborn.And like Stir Blue says you can call authorities but then you are soo busted she will know it was you, it sounds like the dog is depressed to me and that is so sad.
But the little things you can do even the pat on the head and some kind talk to it will help you and the dog.
Im sorry I tend to get really emotional when it comes to helpless creatures but thats who I am and if if it wasnt for people like you and me there would be no balance in the world so I will not back off ever.
Also never think its a stupid pity party that is not it at all you just have alot more empathy than the average person even though its painful its also a gift to be able to see things as they are and from the creatures perspective.