Poorly bred dog. Neuter and return to the breeder. Fear aggression that's gone on for four years now it going to be a bugger to correct, and it sounds like you've got your hands full. Once that turns to the family, I suggest putting an end to it. If the breeder has a brain, she'll euthanize. If not, at least she can't breed this dog. If she refuses to take the dog back, please for the safety of your family and the general public, euthanize this dog. You can't pass that kind of a danger onto someone else, and it's not feasible for you (in your current position) to manage this dog. One slip up, and you'll regret it forever. VERY unstable dog.
Wrath of Grim z Dragon
"Mr. Grim"- Threaten my handler. I dare you.