Every dog we have and had has been an abandoned and/or abused dog. All have ended up being good pets (for us) but all have ended up differently. Some require special precautions such as never allowing small children to be in the room with them and others have turned out close to fine but with some oddities of behavior.
Gracie took several weeks to trust us and then suddenly decided we were hers, let us touch her paws, and pet her however we wanted. She got somewhat protective but not scarily so.
Bourbon is never going to trust most people ever, but she has become accustomed to being with us. She will rarely accept petting unless she comes up and asks for it, which she does every few days. She has to wear a muzzle when she goes to the vet or when we trim her claws or bathe her because she snaps. But she now does the “happy dog dance” when we go to feed her or let her in or out. She still isn’t very house-trained, especially when she feels stressed.
Boudreaux had a very, very hard time accepting our right to tell him what to do (and had a number of other bad habits as well). However, we worked with him a lot and he has turned out to be a good but very energetic dog. We cannot trust him around small children, however, and having had an embedded collar he cannot abide anyone tugging on his neck. He also gets very angry at the smell of raw fish (but he likes it when it is cooked). He also hates fire crackers possibly because he had been shot before he came to us.
Scarlett was injured when she was a puppy and the injury was never treated. By the time we got her she was in great pain and could not use one of her back legs at all. Nonetheless she immediately trusted us completely. We put her through orthopedic surgery to repair the damage, so now she can use all four legs, and she thinks we are the most wonderful thing in the world. She loves all people indiscriminately except for the guys that burst in through the front door one evening. They got a bit of a surprise because she and Boudreaux (jointly 180 pounds of dog) were sleeping in the front hall and took off after them.
Sally has turned into a terrific and trusting dog with one exception. She cannot stand having to get out of the truck into a parking lot. She was found starving and abandoned in a parking lot. She was adopted by a family that suddenly could no longer keep her and they abandoned her in another parking lot. Then we got her. You can see why she might not like parking lots.
My sister’s current dog was also an abused and abandoned dog who loves my sister very much but has a number of quirks and foibles that mean she cannot be near any other dog or a cat or bloodshed will ensue. She is now 14 years old and beginning to be very frail, but we still have to be careful. OTOH my sister wouldn’t live without her for anything and will be heart-broken when the inevitable comes to pass.
We also have had several feral or abused cats, all of whom eventually became friendly with us over a period of anywhere from several months to over a year.
All of these animals took a lot of extra work and patience, some ingenuity, and a very calm and quiet demeanor. We also are very aware of their limitations and so cannot put them into circumstances that other dogs would tolerate such as a dog park or with children.
If you realize the amount of work you will be taking on then quite possibly you can get this dog to adjust to living with you. You may also have to accept that your friends may not ever be able to be around this dog both for their safety and to keep her from panicking. If you can do the work you will get a dog that will love you in its own fashion.