What a messy situation....
Do you know anyone who you could borrow or cheaply buy a kennel from? That way when you have her outside she wouldn't have to be tied up. You could also keep her in the kennel at night if she is used to being outside and wouldn't bark up a storm...of course, that complicates things with her not being spayed, but IDK.
I was able to buy a used kennel and doghouse for Chloe for $70. The kennel is small (6'x10'), but since I wanted it to be used as a crate it is working out nicely. Its a little banged up and the door won't open unless you have it in the right position, but it is much better than spending $300 on a brand new one.
Even though you will have to keep her outside, at least you can house her outside properly and not as a chained dog with no human contact. If she is used to being kept outside, I'm sure coming to stay with you for a while can only be a step up.
I hope you are alble to do something, the poor pupper.
