However, Revell struck in the closing stages to snatch the victory and Slade believes that his side paid the penalty for their desire to nick the three points.
He told reporters: "It was very harsh to lose, we didn't deserve that. We were excellent and got back in the game and we showed that normal character and grit.
"It was an eagerness to try and get down the other end and get the win. We had worked so hard to get back in the game and we were in the dying seconds. And turning the ball over in the dying seconds has cost us dearly."
Orient slip out of the automatic promotion places in the League One table in favour of Wolverhampton Wanderers as a result.