Cristiano Ronaldo scored a second-half hat-trick to underline his status as one of the world's most consistent performers with two powerful headers and a late free-kick to seal a 4-2 win for Portugal while Palermo striker Lafferty had been on the field less than 15 minutes when he was sent off for a botched challenge on Joao Pereira.
Lafferty's was the third red card of a turbulent evening - with Helder Postiga and Chris Brunt already dismissed - and although it had the least influence on the final result, it left O'Neill seething.
Lafferty, a substitute on Friday night but so often a first-choice pick for his country, has struggled to make an impact under O'Neill due to injury and suspension but his latest indiscretion represents his lowest moment yet.
"Kyle's was a very reckless challenge, ridiculous to be fair," said O'Neill.
"I think his team-mates deserve better than that, I feel he let the players down.
"We talk about reliability. We don't have that many players and the ones who come, we need them to be reliable and to do what you ask them to do.
"You want players you can rely on."
Brunt received a more lenient hearing, despite his second yellow card coming when Northern Ireland were 2-1 ahead thanks to goals from Gareth McAuley and Jamie Ward.
O'Neill had asked the West Brom midfielder to operate out of position at left-back and allowed him some leeway as a result.
"It was a bit of a lifeline for them, Brunty's sending off and in the last 20 minutes they showed their class," he said.
"But I have sympathy for Chris, playing him at left-back isn't his natural position."
Ronaldo arrived in Belfast one behind the great Eusebio on Portugal's all-time scoring list, but left two clear of his illustrious forebear with 43 international goals.
It is a statistic that O'Neill feels does not flatter the Real Madrid man.
"It's the sign of a world-class player...one of the greatest you will see in this stadium," he said.
"You have to look at the key moments of the game and say Ronaldo (was the difference).
"When he had an opportunity to exploit space he took a real grasp of the game."
Ronaldo also earned the praise of his own coach, Paulo Bento, whose side lead World Cup qualifying Group F from Russia after their win.
"He is a different kind of player, we recognise that...everybody recognises that," he said.
"Of course we are happy and proud to have him with us and to help us in difficult situations.
"He scored three goals and he was crucial.
"I think he will be recognised as one of best players in Portugal's football history for sure."