Put this clip right after the bad reveal in your edit, once the consequence is clear. Follow it with Directed by Robert B. Weide for a hard fail ending, or precede it with a Metal Gear Solid alert when the character first realises what happened.
About this sound
Soft male vocals sing the opening line 'Hello darkness, my old friend' over quiet acoustic guitar for about ten seconds. It feels somber and resigned, like settling into solitude after everyone else has gone. The clip comes from Simon and Garfunkel's folk song The Sound of Silence.