Losing My Best Friend: A Story of Grief and Guilt

question for you all: what was the most painful moment in your life so far? im asking this to try and free you guys from what you're holding back, you deserve to feel release from your stumped down thoughts, even if its just for a few minutes.. from thinking mine happened around 2020 I had a rabbit I named Meatball since I was around 10-12 I loved him so much and I basically considered him my bestfriend, until around 2 years into having him my mental state grew so bad I found it too hard to take care of him, i felt bad and when i had the energy i would try and sit down with him but he seemed to grow distant from me every time.. I'd cry about it to him even though he never understood, it was around Christmas of 2020 and I was crying to my dad about how I just didnt think I could take care of him anymore, and that I thought about rehomeing him, this convorsation was on and off for a while, until a day came where i was playing on my laptop with my dad, and I genuinely felt happy, until we both heard loud banging coming from his cage, I went to check up on him and i asked him if he needed more water, because that's what he normally does if he needs more water... I then saw him laying on his side, seizing.. I grabbed him out of his cage as softly and quickly as I could and of course I started panicking, I called for my dad and ran upstairs to my mom, I set him on a towel and continued to pet him as he passed... I buried him in my great grandmas backyard with one of my dogs who passed around a year before him, the next day, I kept calm until it was time to lay the box he was in, into the hole he was dug, I kept crying and had a mental breakdown.. til this day i still find myself thinking about him and crying about him, he was my bestfriend and I lost him. I couldn't help but think it was my fault for the lack of attention I gave him suddenly, I just wish I could go back in time and rehome him like I talked about so much, he deserved to be loved and cared for, not ignored and cried to... he deserved better, and im stuck with knowing that he passed basically alone, not knowing if I still cared for him or not. I miss him, and I really hope he knows that, wherever he is.