Betta Fish: Sparky passed away

Ive had him for exactly two years. My boyfriend found him on Tuesday, unfortunately he wasn’t with us. I’ve cried so much, I know he is a fish but i love him so much. Just the day before i got a plant to mimic rice paddy’s, Valisneria, but i hadnt put it in. I was planning it for a while, he never got to see them. I keep blaming myself because the nitrate was 100, and I just did a water change three days before. It hurts so much. I’ve poured hours into his care, probably hundreds, in researching and finding the best plants and the best setup and best foods and i constantly was getting things for him to improve his life. I am heartbroken. Words can’t describe.