Winning against an annoying player?

Hello;

Today I lost one game by a terrible blunder, and won one because of my opponent's incredible blunder (which I present now). Please help me analize how I could have done better on it.

I played against a opponent rated at 1138 (before the game), being mine at 944. He just seemed to me to be a greedy one. He started by disabling the chat (which makes sense, since he only seems to pick games against <1000 players to gain rating I guess). Also, most of his losses seems to come from 900-1000 rated players :P

Anyway...

So this is the endgame... I seriously had lost all hopes of winning and moved my rook to e7 making a last struggle there. White's queen started getting all my pawns so I was planning on resigning soon.

But what a blunder my opponent made!

This is how it ended.