Elderly Relative's Cruelty Towards Cats Weighs Heavy on My Heart

Assalamu alaikum, I need to get something off my chest. There's an elderly woman in my family home who has a terrible habit of hurting any cat that comes near. She uses stones and sticks to drive them away, and sadly, she's taken the lives of several kittens we've had over the years. Even after we made sure our cats were spayed, if a stray kitten somehow ends up in our yard, she finds a way to harm it-sometimes with poison, other times by tying it up and discarding it somewhere far away. It breaks my heart because this happened to a sick little kitten I was nursing back to health. I've tried to speak up, but nobody in the household supports me. Things are so strained that she even forced my mother to leave the house, and now we can't even visit her. It's a mess. I constantly find myself making dua that she faces justice, but I'm ashamed to admit my thoughts sometimes drift to wishing for her death. I know as a Muslim I should strive for patience and leave judgment to Allah, but this anger is eating me up inside. How do I cope with these intense feelings while staying true to my deen?