Dude don't give up. Those are my generic words of encouragement.
But what I really want to say is, I have had deaths before. I was careless and waited too long to med. or mixed the wrong fish without concern. When it is a fish you care so much about and you maybe even cry over you dang well feel like giving up. I would never blame you for selling off what you have and just going fish free for a while. If not forever. Fish keeping we know is not for everyone. We may think it is for us but sooner or later we reconsider what we are doing. We are pulling something alive, something with feelings and needs, out of their home and putting them on display for ourselves. The most selfish act I have ever done if you ask me.
I often times deeply consider stopping this hobby. There are so many reason. Money, time consumption, morals. But I realize it gives me a joy my friends cannot. It gives me a joy a car cannot, my guitars cannot, food can't even make me feel such triumph over nature. I love watching my fish eat and I love watching them play. It sounds demented to me to be so happy to see these fish captive. But we have to always remember, We did not start this, We are not the cause of all fish keeping. We are trying our best to keep the fish already captive alive. We are not helping however, the stopping of the industry. All we can do is help something without a choice live a better life.
On an ending note. You shouldn't give up because you will regret it. Giving up is more powerful than failing. You emotions are more vulnerable. Just take some time and think. Good luck. Much love.