I don't think his death had much to do with the mice. Regurtitation (sorry for the bad spelling) may be more of a sign of what was already making your snake sick. Reptiles hide their illnesses so well they can fool even veterinarians. Eating is not a good indicator of illness. My very sick rescue bearded dragon was eating and pooping fine. But she was suffering from months of a yellow fungus infection and eggs inside of her were crushed and all over the abdomen cavity.

You had invested time, money and love to a pet for 8 years. That is longer than most marriages lol. That is a commitment many will not accept. Feeling guilty and doubting yourself will linger and it is normal. As time goes on, please remember that 8 years of any relationship is worth grieving over and you must have done something right if your snake lived for that long. Sometimes, animals including people are born with things that barely works or fails earlier than others, and it is mother nature's way of keeping life and death balanced, despite man's best efforts to prevent so.