Fusilli: <TobusRex: fxg3? is incorrect
19. BxB, Qxh2+ 20. Kf1, Ne3+!>
If you are saying, as I believe you are, that against 19.Bxg2 black should not play 19...fxg3 but 19...Qxh2+ 20.Kf1 Ne3+, then white has 21.fxe3 and after black plays PxP (either e3 or g3) with check, white plays 22.Nf3 and lives. And if 20...fxg3 instead of 20...Ne3+ white has 21.Nf3 threatening the queen, prematurely placed in h2.
In the line I suggested, 19...fxg3!, 20.Nf3 doesn't work because of 20...Rxf3! 21.exf3 gxf2+ 22.Nxf2 Qxh2+ 23.Kf1 Ne3+ winning.
And taking the pawn with 20.hxg3 meets the line offered by <GrahamClayton>.
I am moving the pieces around but I am not checking with the computer. Maybe there is a refutation, but 19...fxg3 looks like the killing blow to me, while 19...Qxh2+ followed by 20...Ne3+ seems to soften the attack, highly dangerous considering that black sacrificed material already.