The terrible dreams may be a symptom of your sleep apnea - the brain/mind's response to the oxygen starvation it is being subjected to every few minutes/seconds. I don't recall dreaming very often now, and the dreams I do remember are much less violent since starting CPAP. Before starting, I dreamt of crashing my car several times - one I remember particularly vividly because it had me driving off the edge of a cliff with my family. Not a nice thing to do. Since then, I have only had one bad dream that I can remember - just the other night. I was being attacked by a couple of people; I accepted the taunting for a little while, then decided I would defend myself with karate. I started the wind-up, and roared - only thing was, I was roaring in real life and woke my wife, who woke me. I was already in a sitting position! No 'death' for me in that dream! I have a bit of a cold, which may have affected my breathing to some extent, but I am just writing it off to one of those things.
If anyone can "diagnose" dreams, I might take a look but I don't take that kind of thing very seriously. Unless they are clearly premonitory.
Kmod21, may all your dreams be pleasant ones when you are on CPAP!
Diagnosed September 2009, Respironics System One w/ C-flex and humidifier
Aloha nasal pillows
Not a medical professional, just a patient with severe OSA (31) who has done a lot of reading.