What goes on in Vegas most certainly will NOT stay in Vegas here!
Watch it go down (below)!!!
Belt your emotional face off Demi-corn!
And it was pure perfection!
The 21-year-old singer covered the heartfelt and twisted jam, nailing every haunting note!
Before the performance, Demi gushed to the crowd:
"This is my surprise. It's one of my favorite songs. This song means everything to me."
She's the best, isn't she?!
Ch-ch-check out the AH-Mazing performance (above)!