As to my worst nightmare, I've forgotten many. I will say that FLOH (my novel--see above) scared me when I was a teenager just being born again into Christianity. I saw the devil sitting in the church I used to go to. He told me, "This isn't a dream, and it's not over yet!"
The next thing I knew, I was in hell. Scary shit! The second worst nightmare I had was eerily similar in terms of content. I renounced God, and demons drained me of life until the point I wanted--and tried--to take my own life. I also wrote that into a story which became a indie horror film, "Headspace."
Who knows, maybe these night terrors were dreams in disguise? Or maybe, just maybe, they're not dreams, and they're not over yet!