Would you be mad if someone hit your dog?

My dog is my baby. He’s smallish- about 20 pounds. He’s a jack Russell. He’s very well behaved and listens to me without hesitation. the only issue I have with him is when we’re at home he barks when people come over because he is extremely protective over me. He does NOT bite or growl and only barks at home. When he was a puppy I had such bad anxiety I couldn’t even leave my front door. I eventually got out of it but I think that made him very protective of our home. Anyways, when my friend would come over he would bark and run and hide. once she started becoming more comfortable with my house and he would bark she would smack his face and yell at him or hold his mouth closed and smack him. I got PISSED and we’re not friends anymore now. Like who are you to put your hands on my dog? I get barking is annoying but he’s protecting our home. Would this piss you off too? I seriously contemplated fighting this girl right then on the spot over this. I’m not the fighting type but he is like my child since I can’t have children. It pisses me off just typing this out. How you going to come into my home and assault my animal.