Rabbit just died....guilty?

my rabbit was 4-5 years old. we went outside and saw that he had been bitten in the eye by a rattlesnake. we took him to the vet, they put him on life support, but he ended up dying. now im realizing how much more time i could have spent with him. the days that i forgot to give him fresh food, all the times i didn't pet him, when i could have played with him when he was lonely by himself in the backyard. how do i get over this greif and guilt?