At the end of my suffering
there was a door. (1-2)
Doors often represent transitions or decisions, and this door is associated with suffering. The phrase "at the end" can refer to space as well as time. Maybe the speaker is comparing suffering to a long tunnel (like the tunnel sensation of a near-death experience) that leads to a door. Or maybe the speaker is suggesting that people tend to reevaluate their lives after times of mental or emotional suffering.
It is terrible to survive
buried in the dark earth. (8-10)
Being buried alive is high on Shmoop's list of "Experiences We'd Just As Soon Avoid If At All Possible." But what if this terrible situation is just a temporary stage in a spiritual journey to life after death? Okay, we'll consider it, but we're still not happy about it. "Buried consciousness" also conveys a vivid image of psychological or emotional isolation or repression.
Then it was over: (11)
The hardest part of the process—the hard suffering—apparently has ended. But where will the next stage of the process take us? If this is a journey of spiritual transformation, physical death should give way to life in a new form. If this is a journey of emotional transformation, despair should give way to hope. We hope.