Fantastic advice, thank you for interjecting!
The only thing I think
@Rocky998 did "wrong" here (and I'm not trying to berate you or judge you here Rocky, I promise!) is not setting up his QT tank for new fish, and a place or alternative like a breeder box to separate the fish once things started to go wrong - but that's a mistake most of us learned the hard way, whether through an experience like this, or through a sickness passing into our tank. Not something to berate or bash him over.
I've said it here several times and I'll say it again, that I doubt there is a fishkeeper alive who hasn't made a mistake that was fatal to one or more fish. There is such a steep learning curve in this hobby that never ends, and many ways for disaster to strike. Whether someone is willing to admit to their mistakes in public and learn from them means a lot, and Rocky certainly seems willing and able to learn! But people are much less likely to seek advice and admit to fatal mistakes if they are then raked over the coals for them. Especially a beginner, and even more so when that beginner is very young. Seeing experienced, much older hobbyists berate beginners to the hobby for not already knowing everything makes me sad, and ashamed to be part of the hobby at times. It's not a way that encourages sharing and learning, and doesn't save fishes lives either.
You'll learn from this Rocky. While of course it's important not to be flippant about the lives lost and to accept responsibility, it's also important to know that you're not alone in having situations like this happen, that it's actually very common in the hobby, and to take what lessons you can from it so you can hopefully have a better outcome next time. I'm sorry for your loss, and hope that you're doing okay.