Hartz is killing my cat

We moved to a new house and my cats got fleas for the first time in their lives, so we got this Hartz Ultra Guard Pro Flea and Tick drops for cats.

Less than a day after putting it on my 2 year old cat Luna all of her fur starts falling off, she’s lethargic, doesn’t want to play or chase or eat treats. I call the vet and they explain to me that this stuff is horrible and a huge percentage of animals react very badly, that they reccomend washing it off with soap and water within half an hour of application, but in my case it’s been on for too long and it’s already sunk into her skin and she may have eaten some of the hair that fell off as a result so it’s in her system.

So now I’m sitting here holding her in my lap WATCHING HER DIE. I rescued her when she was a feral kitten abandoned outside my house, I adopted a friend from animal control for her, the two of them are closer than sisters. They cry when they’re apart for just a couple minutes. The other cat doesn’t understand why Luna can’t play with her anymore, she’s walking around the room mewing, she even picked up a toy rat and brought it over to Luna to ask her to play. It’s absolutely heart breaking.

She’s the sweetest cat I’ve ever had, all she wants to do is cuddle. She would run up to the door when I got home and jump on my leg like a dog so I could pet her, then she’d roll over so I could rub her belly. When I’m at my computer she likes to lay in front of my keyboard with her paws on my chest and her head resting on my mouse arm like a pillow, and we’ll just hang out like that for hours. She thinks the world of me and she trusts me unconditionally and thanks to these Hartz bastards and their pet poison I’ve killed her. I feel like I’m going to throw up, I don’t know how I can live with myself if she dies.