That is truly sad.
I'm not sure that snakes have feelings and that dieing "hurt her feelings" but as a captive animal they have rights. Those rights include having the bare necessities of life provided for them. The owner was clearly negligent of providing those rights to this animal.
I don't know what you can do about it, now that the snake is dead. You could have reported the abuse to animal control but being a snake, they might not have been much help. There are laws against animal abuse but I don't know how you could prove anything...now that itís dead. It's hard because you obviously know this person very well but maybe report them to animal control anyway...at least they might get a letter saying that there was a complaint about their care of the animal.
Apparently this person did not take you seriously when you voiced your concern. The best thing to do is to act with maturity and let this person know how you feel.
Anyway, sorry to hear about the snake.
If there is anything the nonconformist hates worse than a conformist, it's another nonconformist who doesn't conform to the prevailing standard of nonconformity.