Stray cat found dead on the side of the road and Im very saddened over the tragedy?

Im a huge animal lover and have a very soft spots for unfortunate stray and feral cats. I sincerely believe in TNR (trap neuter release) of feral cats and am a strong advocate for the practice. There are 5 feral cats that have all been TNRrd that i been care-taking for probably a good two years now. Within the past month this new intact male feral cat had been coming around and eating the food I provide for these feral cats. Long story short, i was ready to trap this cat and have him fixed so he would stop chasing the other fixed cats. Sadly to say, when i came home from work, i saw him 3 blocks from my house on the side of the road dead. I feel so sorry, and keep beating myself up over its death. I keep thinking that if i trapped it in time, in wouldn't roamed so far into a busy road. My neighbors say that i do so much for the other cats, and that i cant save them all, but why am I still so overridden with guilt. Anybody have some advice?