This is Going to Hurt by C. Nichols

A horrifying and dreamlike tale of a man trying to save his own soul.  

Wes Geary is in crisis. Haunted and tortured throughout entire life by his own personal pain demon, Wes can’t take anymore. At the end of his rope, he wakes up in a surreal nightmare where his traumatic memories play out in front of him with brutal clarity. With no choice but to face what he has hidden from for so long, he must also take a stand against the violent shadow creature that has left him nothing more than a mass of scar tissue. If Wes is not careful, he'll learn that sometimes even if you win, you can still lose.