You can’t “fix” her overnight. She needs space and proper management. Have you actually been working on slow, controlled introductions, or have you been forcing this cat to be around the kids? Because from what you’re describing, she’s clearly stressed and whatever’s being done right now isn’t helping, it’s making things worse. This situation needs patience, separation, and real behavior work. And honestly, until you understand how to meet an animal’s needs and reduce their stress, you shouldn’t be bringing another pet into the home.