Hi,
My rottie used to have a go through the screen door if they were silly enough to stand there and eyeball him, he simply couldn't see through it. I always took people out to introduce them so that he knew who was around then we would go back inside and he would be fine as he could smell and hear them. I would say that your dog has postraumatic stress as a result of its experience, in the human world we use densitisation so the suggestions here are quite appropriate but will take time.