If I could, I'd send you an aspirin for your 'hurting head'. Just follow your heart with this dog. ( I know where you are "coming from"...I feel the same about animals)
Last spring we "adopted" a stray who had been abused. You can feel where the broken rib has healed.It's still a bump. Ours is a young dog..about 2 yrs. old. As long as YOUR dog is getting along OKwith the feedings you supply, the bone will probably heal in time. (Maybe not correctly, but he can still walk and run with it) WE did NOT really want a dog. We have a 16 yr old cat already. But we have had this rambunctious pup since last June, and now we can have both the cat and the dog in the same room without a chase or a fight. Had to keep more of a control on the dog than the cat. But now the dog knows to leave the cat alone. And the cat reinforces that by hissing at the dog every time she comes too close. But for 9 months, I think we are doing pretty well. As I mentioned earlier, it takes TIME. These animals are not pushovers, and know to be careful, and cautious around people.
I really really hope you can befriend him, and keep him. (He looks a lot like our white/blonde german shepherd who died 20 yrs ago)
God bless.....z