Rotherham manager Paul Warne was left "broken" after his side were relegated with a 1-1 draw at Cardiff.
The Millers were on course to beat the drop after Lewis Wing's early volley sent them to within touching distance of Championship safety.
Rotherham missed a string of opportunities that would have sealed their place in the second tier for another season, and they paid the price when Marlon Pack equalised in the 88th minute to send them back to League One.
"I hope pride will overcome the sadness," said Warne. "I've been asked about my future and all that but I'm absolutely broken at this moment in time.
"We dedicate our lives for 10 months, and right now I can't see any sunshine. But I'm immensely proud of how far this group has come.
"I feel a bit hollow and devastated for the group. I wanted them to leave the stage like heroes.
"There will be different people in the changing room next season, but that group of players should be cemented as gods of Rotherham Football Club.
"There would have been no greater feeling than if Derby had lost 3-2 and we'd won. I don't know when you're ever that ecstatic about anything.
"If someone gave you a new car you'd think great, but if you have something together as a group of warriors to enjoy but would have been amazing, but it's been snatched off us and it feels so harsh."
Cardiff manager Mick McCarthy can now look ahead to next season after taking the Bluebirds from relegation danger to within nine points of the play-offs.
And he wants his players to show the fight they displayed in a much-improved second-half performance.
"It was a hard-earned point," he said. "Rotherham had real intent and were more aggressive, more forceful and better than we were.
"I was annoyed at half-time, it was as meek and mild as we have been and in the second half I thought we responded.
"We didn't deserve to win the game, but I am glad to get a point.
"There is a big difference between running for your lives and running for your dinner and Rotherham were, they were fighting for their lives and I thought their performance reflected that.
"But I did think that late on in the game, if we could keep hold of the ball and progress up then you get nervous, you really do, especially trying to preserve a lead that will keep you in the Championship.
"And they've had chances, we caught them on the break a few times, but they had one moment of weakness and we punished them.
"It is sad for them, but I didn't want to get beaten."
