ymRaisinQg3 fails because after Qe5 Nxe5 white plays fxg3 and black hasn't actually won anything. 1... Ng3+ 2fxg3 Qxg3 3 gxf3 Rg6 is the winning line.
Alternatively, if you don't feel like doing any calculation, Nxe1 gives you an easy endgame.
Also, White is probably a pretty bad player. Ask yourself, from this position, what the hell was white's last move? Somehow, he managed to make a move that didn't involve taking the hanging knight on f3, taking the hanging pawn on e4, or moving his rook off of e1.
This position is taken from a Fabiano Caruana vs Levon Aronian blitz game. I made a mistake and forgot a bishop that is meant to be on F1, which just makes Ng3+ the only winning move, the bishop not being there is also what made the other moves suggested above work.
You can check the game here : https://www.youtube.com/watch?v=fsbBn3bf06A
(this position shows up around 8:40)