Richard Keogh's agent claims the player's seven years of service to Derby was not properly considered when they sacked him for gross misconduct.
Keogh, 33, was sacked for his involvement in a crash that left him injured and led to two team-mates pleading guilty to drink-driving.
"To be kicked to the kerb is a really difficult pill to swallow," Keogh's agent Cos Toffis said.
"He's bled in that shirt, fought in that shirt and cried in that shirt."
Keogh, who captained the club until the incident, sustained knee ligament damage and was ruled out for more than a year after a car driven by Tom Lawrence crashed into a lamppost on 24 September.
Midfielder Lawrence and Rams forward Mason Bennett were fined six weeks' wages by the club, while Derby magistrates' court ordered the players to carry out 180 hours of unpaid work, gave them a 12-month community order and banned them both from driving for two years.
Keogh's role as skipper and the added responsibility that came with the position were factors in his sacking, BBC Radio Derby reported on Thursday.
'He deserved to be treated like family'
But in an interview with talkSPORT, Toffis said he was "absolutely shocked" when his client was dismissed after seven years with the club.
"It was something we were paranoid about, but at no point did we think it was going to happen," he said.
"The only thing I pleaded for is that Richard be treated like family - he deserved to be treated like family.
"Richard played 356 games for the football club and whenever a player commits and dedicates to a football club the way Richard has, I think you become part of that family.
"I don't think I can put into words how much he's hurting and what his family are going through.
"Richard is in a really bad way, it's heartbreaking. Richard's world has been absolutely rocked."
'Keogh will play again'
Asked if Keogh should have known better than to get into the car with his team-mate after a night drinking, Toffis said: "I'm not going to accept that.
"I can't really go into the events of the evening, but I do have a side of the events so I can't accept what you just said."
Keogh had 14 days to appeal against Derby's decision from the point that it was made last Wednesday.
However, Toffis said no conversations had yet taken place with the club regarding a possible reconciliation.
"The decision was made by them, they closed that door when they made that decision and since they did my phone hasn't rung," he said.
"I'm a football agent, my phone number isn't blocked to anyone. If they ring there'll be a conversation of course."
Toffis also said that Keogh, who was originally ruled out for 15 months, is "ahead of schedule" with his rehabilitation and is aiming to return by November 2020.
"He is the most determined character I've ever come across in my life," he added. "If there is one thing he will do, it's play again."