Verbal abuse for a dog is tone, not necessarily the words because they don't always understand the words - just ones they are trained to know, but the tone is what the dog understands and yelling at a dog will scare them or cause them to be afraid. I have rescued dogs for years from bad situations and there is a distinct personality difference for dogs that came from a verbally abusive home.
Giving your dog lots of love and affection should counteract the negative affects that this experience has had, but your dog may not want to go to that home again.
Sounds like you are a great mom to your dog, I would definitely consider alternate arrangements if possible if you need to have a dog sitter again though.
Dog Breeder, Show person, handler, rescue person and trainer