Unfortunately giving you directions here on the forum would be a spoiler, and we are not allowed to do that. Try asking people in-game, or just follow someone out. It can take a while, but ultimately you may feel just a bit better about having to spend some of your own effort getting out.
But maybe a small hint... When you're in the Death Realm, did you look around to the sides of various walkways and ramps, and see some on the bottom? There must be a way to get down there..
