The Pars Community terminated discussions after their final offer was not accepted by Gavin Masterton's camp.
The club later hit back saying the group had failed to provide proof of the initial £250,000 funding needed for the deal.
Amid the recriminations, a tax bill of around £130,000 needs to be paid in the immediate future with Her Majesty's Revenue and Customs having petitioned for a winding-up order in the Court of Session.
Dunfermline will have to pay that debt within eight days of the notice being published and the club have other debts including to their own staff, who received just over half of their wages at the end of last month.
The team are away from home against Raith Rovers tomorrow and, although their Fife rivals have vowed to donate some gate receipts, there is a real danger of the club folding amid the cash flow crisis.
Masterton announced he was stepping down from the board earlier this month and a steering group was formed to help save the club with director of football Jim Leishman and accountant Stephen Taylor fronting rescue attempts.
But Masterton remains in control both in the fact he and his companies own most of the shares and also because most of Dunfermline's circa-£9million debt is owed to him and those companies.
And relations between him and the supporters look to be beyond repair.
A statement from the fans' group read: "The Pars Community has been unable to receive confirmation today from Mr Gavin Masterton's representative that its final, non-negotiable proposal, made yesterday, was acceptable to Mr Masterton.
"Accordingly, discussions between TPC and Mr Masterton's representative have unfortunately now terminated.
"TPC has worked tirelessly over many months now and is extremely upset at the outcome of its endeavours."
In a lengthy statement, the group expressed frustration over a lack of "financial transparency".
TPC said they had supported a proposal tabled by Leishman on March 8 but Masterton, who has not been personally involved in talks, rejected the deal.
TPC added: "Since 8th March, further information has come to light surrounding the severity of the club's financial woes; not least the public visibility around the timetable for HMRC's winding-up order.
"Recognising the immediacy of the timetable for the winding up order, the lack of financial transparency and the increasing caution being expressed by Mr Taylor surrounding the financial position of the club, TPC determined that the Jim Leishman proposal was no longer tenable.
"On the same basis, further attempts by Mr Masterton's representative to modify that proposal, affecting among other matters the financing arrangements surrounding East End Park, were equally unacceptable to TPC, particularly in view of the implications for ordinary supporters.
"It was for these reasons that TPC decided yesterday morning to advise the Steering Group and Mr Masterton's representative that it would be making a final, non-negotiable proposal in a last ditch attempt to save something from a collapsing position.
"The final proposal contained many of the elements of Jim Leishman's proposal but was modified to recognise the implications for a prospective buyer of the perceived severity of the club's financial position, bearing in mind the recent news and the continued absence of audited 2012 accounts for the club and its parent company."
TPC expressed their continued commitment to securing fan ownership but the club's response showed how far apart both parties are.
They claimed TPC's initial proposal involved Masterton reducing his shareholding to 10 per cent and loans to the club being written down by 60 per cent in return for £500,000, half of which was to be underwritten by a "group of named individuals" and the rest raised by fans.
The club added that a working group secured further concessions that would have seen more debt written off and shareholdings diluted further.
The statement continued: "It was expected that heads of terms on that proposal would be signed today and that the TPC would commence due diligence today, which would have led to the financial transparency they had been so urgently seeking and to verify if the proposed offer was a viable solution.
"However, despite repeated requests to demonstrate that the £250,000 of capital was available by the named supporters to deal with the HMRC issue, the TPC were unable or unwilling to demonstrate such availability.
"This led the club to request the TPC to deposit such funds in an escrow account to be released to the club following completion of due diligence.
"At that point the TPC withdrew its offer and subsequently submitted a further proposal, but on significantly more onerous terms than their original one.
"DAFC and its representatives sought a meeting with TPC this afternoon to seek assurances, but the TPC declined this request and have now withdrawn their proposal."
The club added: "The board of DAFC continues to explore all avenues to secure the future of our club as quickly as possible, we will update supporters of progress as soon as possible whilst respecting the financially sensitive nature of the negotiations."