A puzzle from a tight game

Feb 27, 2016, 9:57 AM |
So this is probably the most critical position from my club championship game on Friday night, I didn't play the best move, see if you can find it yourself.
Looking at it afterwards we didn't find this, instead looking at 27... hxg4, but that's met by 28. Ne6 and black has to grovel for a draw.
What actually happened was I begrudgingly took the knight on f8 as over the board I thought hxg4 was too slow and I didn't grovel well enough for the draw and white won in the end.
Here's the full game:
In retrospect I'm particularly disappointed at 12... Nb4 and the immediate 13... Nc6 - too much was hanging or vulnerable for me to leave the knight there.