The chairman of the embattled Police Federation, who yesterday announced his intention to quit, complained he had been "gratuitously and cruelly bullied and humiliated" by the organisation's top brass as he tried to push through reforms.
A message from Steve Williams to members of the Federation's Joint Central Committee, published by MPs today, pleaded for their support and said the bile aimed at him was "a straw that edged on breaking the camel's back".
The letter was published today after the group's former director of communications Fiona McElroy, who was sacked by another federation boss, gave evidence to the Home Affairs Select Committee last week.
It said: "I know some of you have described what has happened as 'venting the spleen' exercises or 'a little bit of bloodletting' but it is simply wrong and is not how we should treat colleagues or indeed as I like to think of many of you, a friend.
"We are all rightly entitled to our opinion but as professional police officers and federation officials, it is how we express those opinions that matter. Whilst accepting emotions are running high in the advent of inevitable change, at times I have genuinely felt that I have been gratuitously and cruelly bullied and humiliated."
Yesterday Mr Williams and the Federation's general secretary Ian Rennie both said they will retire in late May after "a turbulent period" for the organisation.
The Federation came under fire after the Plebgate row and a damning independent review that revealed millions of pounds were held in unaccounted reserves.
Mr Williams made reference to his predecessor Paul McKeever, who died at the age of 57 last year, in the heartfelt letter.
He said: " I seriously need you all to know that the behaviour from some, recently directed publicly and critically towards me, in my opinion is totally unacceptable and for me personally a straw that edged on breaking the camel's back.
"This type of conduct is one of the very things that we as police officers should seek to eradicate from the Police Federation and why the Independent Review needs to be embraced. We all saw what happened to our friend and colleague Paul McKeever and with a young family I do not intend to let the same thing happen to me."
The committee members were told that he had "continually been criticised, ridiculed and verbally attacked" for his support of recommendations for reform by Sir David Normington, who led the independent review.
During a hearing of the Home Affairs Select Committee this afternoon, its chair Keith Vaz MP confronted the Home Secretary, Theresa May, with the e-mail sent by Mr Williams.
Mr Vaz asked Mrs May if she thought all members of the Federation should elect a national chair - rather than the current system, which sees the 30-member Joint Central Committee selecting its leader.
She said: "I think what's important... is that people see and recognise the importance of electing a chairman that will take forward the recommendations of the Normington Review and will take forward the changes that are necessary.
"I haven't seen the exchange of emails. I am concerned about the sort of language you have quoted to me within that.
"But I would say I think that what we are saying is - and what we saw from the Normington Review - is a very real need for a major change within the Federation."
The Home Secretary said she hoped the chairman would be able to "rely on the respect and support of members".
Mrs May added: "I would have hoped the chairman would have had the full support of the Federation, given what the Normington Review showed about the Federation, particularly the significant number of officers it suggested felt there should be need for change within the Federation."
Mr Vaz asked if it would have been better for Mr Williams to remain in position to oversee reforms.
The Home Secretary said: "Obviously, I had expected that Steve would be carrying on and therefore would be taking the work that he'd initiated forward to the next stage.
"It is for him to decide what he wishes to do and he is the best judge of what he feels is right for himself but also for the Federation."
She went on: "So as I say I think the important thing is when looking at the future, that the Federation sees the need to elect a chairman who is going to take that work forward.
"The Normington Review has challenged the Federation in quite a number of areas with its many recommendations but I think it is important, particularly given what the Normington Review discovered and issues around confidence in the Police Federation, that that work is taken forward."
Appearing before the Home Affairs Select Committee, former Home Office permanent secretary Sir David, who was commissioned by Mr Williams to conduct his review of the Police Federation, warned the organisation faced a "very dangerous moment".
Sir David said the resignation of Mr Williams and Mr Rennie could pave the way for members who want to block much-needed reform to be elected as the new leadership.
He said: "I do think they need to think hard about this because the danger is - this is a very dangerous moment for the Federation. It could be that the resignation of these two people will allow the people who want to block reform, it will allow them to be elected."
Sir David said the current system, which sees the 30 members of the Joint Central Committee elect a leader, should be reconsidered.
He said: "I do think that they ought to think very hard about whether they want to elect the next chairman in exactly the same way as the present one, which is an election of the 30 members of the Joint Central Committee.
"That will just reinforce a sense that that council is distant from its members.
"There are alternatives to that. They could let any members of the branches put their name forward for election, they could widen the suffrage."
Earlier, Sir David told the Committee: "Steve Williams has been under sustained attack from within the Federation from the moment he decided to set up this review.
"There was a motion of no confidence in him at the last annual conference and he has to sustain a great deal of personal attack."
He added: "What is so dismaying about this is it happened immediately after we had published a report in which we said that it was the tendency of Federation representatives - some of them - to target individuals rather than to argue about the issues w ithin a few days of the report being published, they were at it again."