Sroubek appears to become angry that his estranged wife had sent a letter of support for his immigration case to his lawyer without letting him see it first.
He accuses her of changing her mind about letting him see the letter, and linking that to a person she was dating.
"You were completely fine, you were absolutely fine two days ago. All of a sudden ... it is because of him? What the f*** is he?" Sroubek shouts in the recording.
"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?"
She tells Sroubek that she shouldn't have to let him see the letter she wrote because it is from her, not Sroubek and her, and then accuses Sroubek of threatening her.
He pushes back, saying he is not threatening her.
"The day before yesterday, you go out with this prick, and all of a sudden everything is changing. Like, you know what, I'm not going to f****** let it go. F*** off," he said in the recording before hanging up.
It is unclear if Sroubek is referring to Mark Davey, who the estranged wife is reportedly in a relationship with.
Sroubek made the phone call from prison and it was recorded by Corrections and released to the estranged wife under the Official Information Act.
Mitchell, who met with the estranged wife yesterday, said the recording showed that Sroubek had been putting his estranged wife under a lot of pressure.
"It's given us a clear window into the type of verbal abuse, coercion and threats that she's been facing for a good 12 months prior to us hearing this tape."
He said she was under so much stress that she had left New Zealand, though has since returned, and was so scared of Sroubek - a convicted drug smuggler - that she had changed her number and address and had a police safety plan put in place.
"She didn't want to be dragged into the public. But this has visibly had a massive impact on her."
Mitchell said that she and her family felt like they had to go public after Winston Peters had called her a "National Party informant" in the House, and again in response to the letter Sroubek wrote to the Herald.
Questioned about this in the House, Peters has said that National has never responded to his description.
Mitchell said Peters' words amounted to character assassination and it was "totally, completely unacceptable".
"The worst part is a young lady, already subjected to some pretty horrible stuff in terms of threats from someone with a pretty unsavoury background with strong organised crime and gang connections, who was then brought into this House and [subjected] to a smear campaign and character assassination."
Mitchell said the whole saga smelled of a cover-up.
National has repeatedly asked the Government about who has lobbied on Sroubek's behalf, and the Government has declined to name anyone because of privacy reasons.
Last week Prime Minister Jacinda Ardern said that Richie Hardcore, a Sroubek supporter and acquaintance of hers, had texted her about the original decision to grant Sroubek residency, but it was unsolicited and she did not respond.
National have asked for the her to release the context of the text message, but Ardern has declined, saying it could set a precedent for the thousands of private texts she receives.
Sroubek is in prison and facing deportation after Immigration Minister Iain Lees-Galloway flipped on his original decision to grant New Zealand residency.
The dramatic about-face followed political barracking including claims from Mitchell in the House that Sroubek had pressured the estranged wife to support his residency.
In his letter, Sroubek said that the National Party had been drawn into the collapse of a marriage and is being fed "false claims" under Parliamentary privilege about her safety.
"All I can say about this to New Zealand is that you need to follow the facts. They do not support any suggestion that I have threatened my ex-wife or, ludicrously, burgled my house.
"I take this chance to place on the record that my wife has never been threatened or is under threat from me. I have never had any complaints of violence made against me by anyone."
He said his former wife was already in a new relationship with underwear manufacturer Mark Davey when she wrote a reference supporting his bid for residency.
"It wasn't made under any duress and there were absolutely no threats."
