The last mistake before you lose

What a disastrous defeat I had this afternoon playing in chesscube!! After a nice and tense game, I get check at move 39, then from the only few possible moves I choosed the only death path to Kg6??, hence followed by sudden and fatal checkmate with Qh8#.

Chess teach us humbleness and urge us to think carefully before action.

Lesson learned.

The game:

[Date "2013.07.23"]
[White "meimran0402@chesscube.com"]
[Black "amarjen@chesscube.com"]
[Result "1-0"]
[Eco "C20"]

1.e4 e5 2.Qh5 Nc6 3.Bc4 g6 4.Qf3 Nf6 5.d3 Nd4 6.Qd1 c6 7.Be3 d5 8.Bxd4 exd4
9.exd5 Qe7+ 10.Ne2 Nxd5 11.O-O Bg7 12.Re1 O-O 13.Nxd4 Qc5 14.c3 b5 15.Bxd5 Bxd4
16.cxd4 Qxd5 17.Re7 b4 18.b3 a5 19.Re4 Rb8 20.Nd2 Bb7 21.Nc4 Rfe8 22.Rxe8+ Rxe8
23.Qg4 c5 24.f3 Re2 25.h3 h5 26.Qg3 Qe6 27.Nxa5 Ba6 28.dxc5 Bxd3 29.Rd1 Qe3+
30.Kh2 Qxc5 31.Rxd3 Qxa5 32.Qb8+ Kg7 33.Qg3 Qxa2 34.Rd7 Qxb3 35.Qf4 Qa2 36.Qg3
b3 37.Rb7 b2 38.f4 b1=Q 39.Qc3+ Kh6 40.Qh8# 1-0