There is a product called Feliwell, a diffuser you plug into the mains. It gives off calming, odourless(to us) pheromones and helps settle cats. I'm in UK, but there must be a similar diffuser product in USA if you live there. Time will help. It's important not to smack or shake, or get angry (hard, I know) or things will escalate. If attacked by any cat for any reason, one should try not to react at all. (very hard!) Staying still and making chirrup noises will prevent provoking things further. I hope Meghan can try to do that, but it takes courage!. You must find this all very upsetting, I feel for you. I've had cats for over sixty years, and we all love them so much don't we?