Matt Mauser -- who lost his wife in the helicopter crash that also killed Kobe and Gigi Bryant -- gave an emotional audition for "America's Got Talent" on Tuesday ... and the performance is incredibly moving.
The 51-year-old shared his tragic story with judges Simon Cowell, Heidi Klum, Sofia Vergara and Howie Mandel ... before singing a rendition of "Against All Odds" by Phil Collins.
Mauser -- who met Christina at a bar in 2004 -- broke down his final memories of his wife .