I'm so sorry to hear about your loss. I had a puss like this, who affected me in the same way, and 18 months after losing him so young I still find myself talking about him a lot. He really was one of life's very special characters, and I never thought about him as a cat, just a wonderful soul in a cat's body.
Because he was such a character I lived in constant fear of him getting himself into trouble. He was run over twice but both times survived wiith very little injury, but he never learned. Cats like this just have to take their chances in life, I realised that, and we have to rely on their savvy and survival instincts. We simply can't wrap them in cotton wool their whole lives. George lived his life to the full, as did my Mo, who ironically did die young, but of cancer rather than an accident. But he packed 15 years of living into his 7 short years of life. It sounds like George was the same. He brought a special sparkle into your world, but sometimes the brightest stars burn for the shortest time.
Guilt is a normal part of grief, and a wicked and all consuming part. We all feel it, whatever the circumstances, but it's not real. It really was not your fault, you must believe that. Sadly some creatures are not destined for a long life and that was George's fate. But what a wonderful life he had with you, finding his soul mate as well. He was as blessed as you were, and you should be comforted by how much good you brought to his life.
You will feel dreadful for a long while I'm afraid, so just cry all you need. It will eventually hurt less, honest, and you will remember the good times without being overwhelmed by the loss. He was a special treasure who you will always remember, and you were very lucky that he spent his short life with you.
We all understand how you feel so keep posting on here if it helps.
Take care.