Thanks you guys, I really appreciate it. I think what makes it so hard to deal with is that, a few days before her death, she was perfectly healthy and fine. But my dad gave her too much flea medication, and it caused her nervous system to shut down basically. She had to be put down because she kept having seizures and wouldn't stop. Also, she was only about 18 months old.
My mom drove all the way to my dorm so she could tell me what happened in person, and my roommate had to watch me break down and cry in hysterics. It was awful. That kinda marked the beginning of when I started being severely depressed cause 2018 was the first year that I've dealt with so many close deaths. I've dealt with depression most of my life, but it's been horrible for the last year.
We have another cat named Xander who also reacted badly to flea medication, but luckily he was big enough that he survived (he weighs about 20 lbs, while Daisy was only about 7-8 lbs). Daisy was his best friend since they were both kittens and we got them around the same time so they grew up together. He hasn't been quite the same since, although he's still a very good cat. I also have two other kittens who are about a year old now. I miss all my cats very much while I'm at school.