Am I Overreacting?

Our family has a puppy. And we love him but he gets into everything. And he gets into trouble a lot lol. But this morning I could tell my sister and my mom were fishing for an argument. Because my sister called me and said “mom needs you to do etc etc, and don’t get mad at me because that’s what she said”. And I’m like okay whatever. But then I get downstairs and they’re being nasty and rude to our puppy. Calling him names and whatever. And my sister punches him on the side. And I was like “No! You can’t hit him just because you feel like it, that’s wrong” and my mom goes “you don’t care you’re just throwing your weight around, you’re being an asshole” and then she talks over ME, and then accuses ME for talking over her! Sometimes it feels if I don’t 100% CONDONE what they do, they’ll come after me. Am I in the wrong?