What Blanche reveals to Mitch about her past. How does this event help explain blanche's current mental state?

When Blanche reminisces about her dead husband, Allan. She admits to Mitch that she was unable to fill a need for him, and shortly after the wedding she caught him with an older male friend. On the dance floor that evening, she confronted him about what she'd seen, and he ran out of the hall and shot himself in the mouth.

At the end of her speech, Mitch comforts Blanche, saying that they both need somebody and perhaps they might be that somebody for each other, and he kisses her.

During the telling of the story, we can see and hear that the music stops with the gunshot – she is not just remembering but reliving, and the death of her husband stopped the music in the dance hall but also stopped the music in her life. "And then the searchlight which had been turned on the world was turned off again and never for one moment since has there been any light that's stronger than this kitchen candle." Allan's death shrouded Blanche's life in darkness, both the kind that sucks out happiness and leaves only despair, but also the kind that she hides in to avoid the flicker of the unforgiving light. She retreated into herself after this trauma, cloaking her fragile mind with shadows and delusions, and only sneaking out to find comfort in the embrace of strangers, to allow her to feel something that was alive.