Someone hit a stray cat and I'm so angry about it

As-salamu alaykum, I need to get this off my chest. There's this stray cat that started coming around our house, and we've been giving her milk and food whenever we can. She got really comfortable with us, coming in and out, and my whole family loves her. But my parents won't let her sleep inside, so at night she goes out, and sometimes she sleeps on the window sill, which we're fine with. Today, I heard a cat fight outside-it was another stray with our cat, just hissing and meowing, nothing too bad. Then some boy, with no respect or fear of Allah, came and kicked my cat with full force in her stomach, and she fled. I don't know where she is now, and I can't go look for her. I just want to know: is there a sin or a punishment for what he did? And if she dies from the hit, does that make it an even bigger sin? Jazak Allahu khairan for any guidance.