"Seriously, do you want me to do something stupid? Do you want me to send somebody to talk to you because you are doing crazy stuff?" Sroubek says in a desperate voice in the recording.
She accuses him of threatening her, but he denies this in the phone call.
In the new letter, Sroubek said he had become "frustrated" about his estranged wife's apparent change in not allowing him to see the letter.
He did send people to see her - mostly women friends of hers - to ask her to talk to him, but she rejected them.
"There is no way in this whole wide world that these people could be considered a threat."
He said some of the visitors were distressed and this could have been interpreted as threatening behaviour.
"It is also doubly distressing for me that this suggestion of a threat could have been construed by the Minister of Immigration as a factor in reconsidering my immigration status when it was anything but a threat – at worst it was a cry for help."
But Mitchell said that the estranged wife moved to a different address after the unsettling phone call in May.
He said she also contacted her lawyer to say she was worried for her safety, and was moving house and cancelling her phone.
"No one knew where she was to put pressure on her to talk with Sroubek. This is completely false," Mitchell said.
Sroubek said it was "disappointing and hardly fair" to only release aspects of the call to the public, but Mitchell said many journalists had listened to the entire call.
Sroubek said the breakup of his marriage had become "a political football".
"All I am asking of Mr Mitchell is that he let me and my former wife resolve our marriage break-up away from the glare of Parliament and the protection of half-truths."
He said the National Party was "abusing their positions and exploiting my ex-wife".
"I simply want to settle my marital position and move on and be happy. I wish the same for my ex-wife."
Mitchell said that the National Party had only put information about the estranged wife in the public domain in response to allegations that were wrong.
"The only information that she provided was at the beginning of this process when [Immigration Minister Iain] Lees-Galloway made his decision. It was quite simply to say she had provided a letter of support under duress.
"Although she had all the other information, she only revealed that in response to either the Government attacking her or Sroubek making public statements through media.
"It is the Government and Sroubek who continue to bring the matter into the public arena."
