There is not sadder psalm that Psalm 88

it gives an extensive vocabulary of death
Sheol- 88:3; Pit- 88:4, 6; Dead/ death- 88:5, 10, 15;  Grave- 88:5, 11; Dark/ darkness- 88:6, 12, 18; shades- 88:10; Abaddon- 88:11; land of forgetfulness- 88:12

He describes God as being behind his problems- 88;6, 7, 8, 14, 15, 16, 18

Lessons from Psalm 88
1. Some suffering in this life may never end
2. He does not give up on God and continues to pray
3. It makes us long for God's blessings and eternity

Jesus as an answer to Psalm 88
While Psalm 88 is not quoted in the NT and applied to Jesus, in many ways Jesus lived out the experiences of the author of Psalm 88.  
88:3 He is full of troubles- Mark 14:33-34
88:5 He was cut off from the land of the living- Isaiah 53:8
88:8, 18 He was shunned by those closest to Him- Mark 14:50-52
88:18 Darkness was his companion- Mark 15:33
88:10-12 The resurrection of Jesus transforms the questions expecting a no answer to a yes answer.