Betta Fish: My sweet Ritual passed :(

I’m devastated. I’d gotten this sweet creature just about a year after my first betta passed due to an accident with decor in his tank. Im not even fully sure what happened then, it was just as devastating as the loss of Ritual. I’d only had this sweet boy for a few months and had gone to buy him some extra plants and a cute Halloween decoration just hours prior. When I noticed he was looking a little dull…and his fins looked off. I immediately panicked. Now mind you, I’m a college kid who works healthcare. So I’m not in my dorm ALL the time, really only to sleep at this point. I sat and watched him for a bit. My roommate had told me that one of her friends who stopped by earlier was a little worried about him. I feel like a TOTAL failure as a fish parent because how could I have not noticed sooner?!?! He was incredibly active the night prior to today, I’d had a rough day so my best friend and their girlfriend took me out for about an hour then I came back and found him dead. I immediately scooped him out and held him and started crying when I noticed his fins were quite literally DISiNTEGRATING in my hands. I’ve never felt worse in my life. I have another tank at my parents house that’s a 20 gallon Cory tank and in all the time I’ve had fish I’ve NEVER experienced something like this. It was genuinely horrifying, my best friend wants to take me to get another Betta because my fish are incredibly important to me and caring for them is my own little motivational day to day task as someone who struggles with mental health and they bring me a sense of joy and i love caring for and having fish. But it feels so wrong to go get another betta. I’ll be testing the parameters and doing water changes and letting the tank cycle before I consider getting another betta. I feel so so bad for not noticing.