I won't provide an accurate analysis, however I'd say you underestimated too much white passed d pawn.
28 .. rxc8 is the final blunder. You didn't have to take that rook. This give to white a free queen! You had to mantain the control of d8, perhaps with something like Ne6.
In the opening you did something inaccurate too. Defend c4 pawn in Queen Gambit is notorious bad for black, who should develop instead, since c4 in undefendible in the long run aside some particular variations.
http://live.chess.com/live?v=2013082201#g=593660645
Analysis? Could I of won?