You did very well, amigo.

From a self defense perspective (in this case extending to your class as well), you used "necessary force" to control the situation. The staff was effective in keeping them from escalating their attack. Had they pressed you harder, then perhaps drawing the gun might've been necessary.

I certainly would've given the owner a lot of grief. I would also be on the phone to 911 immediately after to report the incident. Too bad you didn't get pictures of the incident. The owner should lose her dogs now, before she or someone else gets seriously hurt. She's demonstrated an obvious indifference/incompetence in proper handling in public, and her reiteration of the violation only reinforces her willful disregard for the safety of her dogs and other people. Had it been me, the outcome would likely have been two dogs in the vet hospital and one big human in the ER.