well... i wouldnt expect less :P think, exactly what scared you, was it the fire? her words? or her existence?
hospitals are tied with pain... whether it is from injury or death. white is a symbol of purity. yet your in a hospital. so it makes sense, why your mind would tie the two. fire, assuming you mean great big fire, bond fire, or out of control, means distruction. if your mind told you death, it means death is an important factor. (im basimg this off of most people in the western culture which im assuming you are. do any of these have a possible double meaning?)
Hi, if you want truly understand your dream - analyze your real life: for example - if you have done something wrong or hurt someone, then this dream means that you will pay for your actions; and so on.
Sometimes dreams are just nightmares - if you watched some freaky scary movie like Ring, then this is normal ;)
But it is a bit out of logic - "I die with your soul", she means that she will continue to live and follow you till the end. I would interpretate that it is not a warning or bad meaning, it is more like a promise - maybe you are keeping a secret (the secret itself could be big and bad).
At first I thought that too, but I personally never heard that soul could die - many teachings refer to soul as immortal, only some talk about reincarnation and others don't.
Maybe shy used that expression "die with your soul" to emphasize that IT IS FOREVER, because soul will never die.