I'm furious at my wife not checking on a potential fire
Why would you be furious at your wife for not checking on this fire?
She could have been in danger!
It is ok to be angry at someone for leaving a fire unattended. She could have been injured or burn a house down if things went wrong.
I expected her to get burned and die. She deserves it.
While it's okay to be upset with her for her carelessness, wishing death on her seems a bit harsh. I feel like there are other issues there that might serve you well to address. You two should talk things over so that these feelings of violence can be taken care of.