She looks precious. That face is to die for. I would have done the same thing, not just because it's a boxer, but I can't stand by and see something helpless get hurt like that. 2 of my dogs were rescue dogs and they thank you over and over again for saving them. Also, strays seem to be attracted to me! Every time I walk the dogs, I swear an animal is always missing and I find them! I say animal because one time I found a ferret. My Petey used to get lost...a lot(whether it was climbing the fence or darting out of my sight). He would chase cats, then can't get back to his home. When I found him, he looked at me with his wrinkled face that said "FINALLY! What took you so long?". LoL.
You did a great thing. Someone might have hit her again if you hadn't picked her up and it could have been worse. I always say my animals come first (I don't have skin babies) and I would max out my credit cards for them.