A British Broadcasting Corporation (BBC) programme, to be aired on Thursday, has accessed these previously unpublished text messages from the prosecution files in which Anni reportedly told her cousin, Sneha, about her troubled relationship with Shrien months before her death.
"I don't want to marry him...I'm going to be unhappy for the rest of my life...One cannot even hug him...We have nothing in common," reads one of the texts, which is one of the first pieces of evidence to emerge from the South African police files.
Police have accused her husband, Shrien, of hiring a team of hit men to kill 28-year-old Anni, while holidaying in Cape Town in November 2010.
However, the 33-year-old Bristol-based businessman, fighting against his extradition from UK to South Africa, has always maintained that he was forced from a taxi by carjackers who drove off with his wife and killed her.
A British court rejected Shrien's plea to remain in the UK in July, but his lawyers are fighting his extradition at the Supreme Court.
The prosecution is expected to use these messages to prove the extent of unhappiness in the relationship which may have led to the violent end.
One of Anni's messages from September 2010 reads, "Fighting a lot with Shrien. Wish I had never got engaged."
The last message sent by Anni from South Africa to her cousin said, "Hard to explain but I'll call you soon as I return. Hate the word divorce."
Meanwhile, Anni's family has filed a complaint with the BBC over the documentary and are upset they were not asked to take part in the programme.
Anni's uncle, Ashok Hindocha, has written to BBC director-general Lord Hall about the family's concerns and accused the corporation of acting callously and insensitively.
Anni was killed by a single bullet wound to her neck after the taxi the newly married couple was travelling in was stopped by gunmen in Gugulethu township, near Cape Town, on November 13, 2010.