For future reference, try not to focus on what monies you added to the pot preflop or postflop. This will cause you to stay in. Instead, when your instincts tell you that you are beat, just fold. A wise poker player is one who folds when he/she realizes that he/she is beat. Additionally, It was a wise move to call seeing that indeed you hit a pair. However, you should have thought whether someone may have hit a three of a kind on the flop since there was some heavy raising pre flop.