Maninder Sambi also subjected his elderly mother to a vicious beating and exchanged texts messages with his partner saying they "hoped that she would die".
Maninder and his wife, Navjot Sambi, were jailed for a total of more than seven years after a court heard the pair cynically exploited Bhajan Sambi when she was suffering from depression.
A jury at Leeds Crown Court were told the couple set about "portraying to the world" that Mrs Sambi was instead suffering from dementia.
During the deception they forged a letter purporting to be from an Indian hospital which stated she was suffering from the debilitating condition.
They also committed fraud by taking out a Â£100,000 critical illness insurance policy against Mrs Sambi before claiming she had dementia.
The court heard Mrs Sambi suffered a "cascade of bereavements" during 2009 and 2010 which led her to receiving treatment for depression.
Those bereavements left her in possession of a home which had equity of around Â£230,000.
A judge who jailed the couple said they began a deliberate process of "belittling and assaulting" her good name.
Maninder was then able to obtain power of attorney over his mother's financial affairs.
He abused that power to set about buying a new home for himself and his wife.
Attempts were made to use the equity in the property owned by Maninder's mother to buy the house.
Maninder went to an HSBC bank branch in Chapel Allerton, Leeds, in order to access the money.
He was told by a member of staff that it was an inappropriate use of his mother's funds.
Jurors also heard how the couple deliberately isolated Mrs Sambi by monitoring and hacking into her social media accounts.
In April 2016 Maninder subjected his mother to a repeated assault by punching her and banging her head against a door.
Mrs Sambi was left with painful bruises to her body.
Maninder and Navjot, both aged 34, both of Carr Manor Road, Leeds, were found guilty of conspiracy to steal, fraud and forgery after a three week trial.
Maninder was also found guilty of assault occasioning actual bodily harm.
During the trial Maninder tried to blame his wife for the offences, claiming she was "the financial brains" of the family. He was jailed for four years, three months.
Navjot blamed her husband, saying she was "subservient" to him. She was jailed for three years. The court heard the Sambis have two children and continue to deny committing the offences.
Jailing the couple, judge Robin Mairs said they were equally to blame for the deception.
He said: "I find that this was very much a partnership. You knew she was vulnerable and you preyed on that vulnerability."