I see so many mistakes in the end game.. Your opponent could have surely mated you much more efficiently. I think you were perfectly in the green. If an opponent whoops my ass because they thought for twice as much time as I did I consider it fair to try and win on time. Either way, he could have probably mated you in 6 seconds, so it's his own fault. You shouldn't have given up.
The Never Ending Game?

consider time being how long until the enemy troops rations run out and they starve. You starved your opponent to death so congratulations .

If your opponent didn't want time to be a factor in his game, he shouldn't have played a timed game. Fischer was known for not only outplaying his opponents on the board, but by beating them psychologically by dragging play out into matches of stamina. I think you were well within your rights to play until the bitter end on a timed game.
I just played a game, where I admit. My opponent WAS destroying me. He had about 21 seconds left on his clock, whereas I had around 8 minutes. Here is the game.
He could have ended it much earlier, after I won he left. He had 6 seconds left, it seemed as if he gave up trying to mate me. Called me a name, and now im here. What should I have done??? Should I have given up? Or did I do the right thing? After all it is war..