Was I a bitch or is my sister overreacting?

Right so I’m 22, my sister who’s 26 has a 7 year old daughter. They came over yesterday, her daughter really likes my dog, my dog absolutely hates her honestly. She annoys him everytime she sees him so he tries to get away everytime. I mean to be honest she’s not been raised great. I don’t like kids and I don’t want kids, but I can appreciate a nice kid. She’s just a little spoiled brat, always throwing a fit over anything and always has to get her way. Anyway, she was playing with my dog, I have a maltese so he’s small. I hear him screaming. I turn around and she’s looking at me. I ask her what did she do to him, she says nothing. A couple minutes later he whines, I ask her again what she did and again, she says nothing. My sister didn’t say anything both times, so I turn around a bit to face her and a few seconds later I see this little shit pulling my dog’s ears and he screams in pain again 🙃 my blood was boiling, I literally wanted to smack the shit out of her. I got up and ran towards her, grabbed her and shouted at her what the hell do you think you’re doing to my dog?! Would you like it if I pulled your ears or hair what’s wrong with you?! Yeah I know I grabbed her quite hard, I was annoyed 🙄 she instantly started crying which I had no reaction to, I went to comfort my dog. So my sister is now mad at me for how I treated her daughter. Well I’m sorry you don’t know how to discipline that little brat and at this age she doesn’t know how to treat animals. They have two dogs themselves, so I bet if she did that to my dog she does it at home too and my sister doesn’t say anything to her. So my sister told me to go fuck myself I’m a horrible human and I said her daughter isn’t welcomed in my house anymore until she knows how to behave around animals and to respect my dog. And now my mom is being in a mood with me because she’s saying I was rude to my sister. Do you think I’m in the wrong? Should I apologise?