now thursday night the foster brought her over
You keep saying foster...who is this foster and what rescue group do they belong to?
First of all, don't try to pet the dog. It's obviously very scared and lack of confidence is not a normal APBT trait. They are generally
very confident, social butterflies. You need to back off and let the dog come to you. It will eventually happen. If I were you, I'd call back this "foster" person and return the dog. Tell them to socialize their animals before adopting them out!
The "fosters" introduction to your home, while he/she was on the right track, was not long enough. A few small visits and then POOF...foster is gone. For a dog lacking confidence and obviously very sheltered (even with this foster person), that's waaaay too soon.