Using the fact that your dog is a rescue as an excuse for why she slipped her lead, charged my dog, and tore a chunk of out him is really shitty and means nothing about your dog and everything about your sense of self-righteous entitlement.
Don't break your arm patting yourself on the back for "rescuing" a dog that's so hellbent on - and built for - fucking up other dogs. Attacking another dog with no prior contact or provocation is indicative of temperament that is not compatible with a family pet. If this behavior is any indication, your dog should have been euthanized.
The only reason why I'm not reporting you to the county is that you paid my dog's vet bill without me even having to ask. I hope you learned a lesson that your son is not capable of controlling your menace of a dog.