Your flop bet was your fatal mistake. With $475 in the pot and potential draws on the board, you should have fired in the neighborhood of $500. This puts him to a decision for all of his chips, and of course, if he moves all-in you would have to call because of the pot odds (he had approx. $800 left). You see how the bigger bet forces your opponent to make a decision right then and there and prevents you from being bluffed out of the pot on a later street. In general, you should always be looking to make plays which leave your opponents, and not you the difficult decisions.