Craig Brown says he and his Aberdeen players are deep in despondency after squandering what he thinks was a golden opportunity to reach a cup final.
The Dons, whose last success was the League Cup in 1996, were beaten 2-1 by Hibernian in the semi-final of the Scottish Cup at Hampden.
"I can't express how despondent that dressing-room is," said manager Brown.
"It is really a depressing place to be in and rightly so because we feel we've let the fans down again."
Hibs reached their first Scottish Cup final since 2001 - a year after the Dons' last losing appearance - thanks to Leigh Griffiths' winner five minutes from the end of normal time.
"We will never have a better chance to get to a cup final," said Brown of the defeat by the side sitting second bottom of the Scottish Premier League.
"Last year, when we played Celtic twice, they were flying and were the best team in the country at the time.
"Hibernian and ourselves, there's nothing in it really and we had the opportunity when we got it back to 1-1 to go on and certainly not lose as softly as we did.
"We only have ourselves to blame."
Aberdeen, whose recent history is littered with shock cup defeats, were a goal down after only three minutes through Garry O'Connor.
"I think the occasion got to a number of the lads again," Brown told BBC Scotland.
"We tried to eliminate that and make them calm and assured, but we didn't really play in the first half at all.
"And, when we got the equaliser, I thought 'we've got the ascendancy here' and we did for a while, but we didn't make the extra pressure count.
"It's another game where our goalkeeper has not had a save to make in the match but we've lost two goals."
Rory Fallon equalised for the Dons after the break, but Griffiths made sure of victory for Pat Fenlon's side.
"We must credit Hibs," said Brown. "We will accept the defeat with humility and dignity and wish Pat Fenlon all the best in the final.
"Of course, the two strikers who scored against us are always dangerous.
"I thought we handled them well for most of the match, but they only need a half chance and they scored."
Fraser Fyvie was introduced at half-time and the midfielder helped the Dons take control of the game.
However, Brown defended his decision not to start the 19-year-old because of a lack of match fitness due to an injury picked up in the quarter-final win over Motherwell.
"The team that beat Motherwell didn't appear today," lamented Brown.