A lovestruck woman cleared of trying to kill her mother by poisoning her diet cola has been jailed for three years after being convicted of acquiring a biological agent or toxin.

Kuntal Patel, 37, was accused of giving her “controlling and selfish” mother Meena the ricin-like toxin abrin after she forbade her to marry her fiancé.

Patel had allegedly dreamed up the murder plot after becoming addicted to television series Breaking Bad and watching an episode in which a character, drug lord Walter White, kills an enemy with ricin-laced tea.

Patel, of Plaistow, east London – who was a volunteer at the Olympics – admitted fantasising about killing her mother, a magistrate, who was said to be hell-bent on breaking up her engagement and to have bullied and beaten her.

Last month Patel was cleared of attempted murder but convicted of acquiring a biological agent or toxin. She had previously pleaded guilty to two charges.

Sentencing Patel at London’s Southwark crown court, Mr Justice Singh jailed her for three years for acquiring the biological agent or toxin, and 18 months for attempting to acquire a biological agent or toxin, to run concurrently.

Singh said he believed she had been forced to endure “a prolonged period of severe stress” in the two years leading up to the offences, which took place last December and January.

He said: “It is clear that you were a devoted and obedient daughter. It is also clear that your mother was a devoted and caring mother, who worked hard to raise you and your sister, having been separated from your father when you were very young.

“On the other hand, in the two-year period leading up to your offences, she subjected you to a barrage of abuse, often verbal and at times physical, for example slapping you.

“She would send you emails and texts of the most vile kind, abusing not only you but also your friends and in particular the man you wished to marry.

“You found yourself in the autumn of 2013 torn between your devotion to your mother and family as a dutiful daughter, and your desire to find happiness for yourself with the man that you wanted to spend a lifetime with.

“Ultimately you could see no way out and became increasingly depressed and isolated, contemplating killing your mother and yourself.”

Patel is the first person ever to be sentenced under the Biological Weapons Act 1974.

The two-week trial had heard that Patel, who was brought up a strict Hindu Gujarati, had never had a boyfriend or a Valentine’s Day card, and wanted to settle down and have children.

She struck up a relationship with Niraj Kakad, from Phoenix, Arizona, on the Asian dating website Shaadi.com and the pair got engaged on Thanksgiving in November 2012.

But her mother is said to have locked Patel in their home and beaten and bullied her in a bid to get her to stop seeing Kakad.

The relationship buckled under the pressure, and they broke up. Driven to despair, Patel told how she slumped into a depression and became suicidal, and began searching ways of killing herself on the internet, scouring the “dark web” for poisons.

She admitted trying to buy abrin to get her mother “out of the way”.

The Barclays graphic designer said the comments were part of a wild fantasy world in which she imagined herself as Walter White or a “Mexican drug warlord”.

She wept in the witness box as she insisted she never actually poisoned her mother.

She told jurors: “By this time, because of the messages I received from my mum, and because I couldn’t cope with it and I wanted to escape from it all, I started to fantasise about trying to kill myself or my mum.

“It was as if I was thinking through it as if I was in my own TV programme or a character in Breaking Bad. I was in a really strange place in my mind.”

The poison was allegedly hidden in a red wax candle and delivered to London, but Patel – who had paid £950 for the toxin – said she panicked when she picked up the package and threw it away.

The court heard she later decided to buy another dose but was caught after authorities posed as the dealer she had contacted the first time.

Peter Rowlands, mitigating, said: “The defendant, over a period of two years, found herself in a pressure cooker of emotion. She looked to the one person, her mother, who might have shored up her increasing emotional distress.”

He added: “A two-year period ended in a personal crisis akin to a nervous breakdown, leading this young woman to behave in a way that now frankly horrifies her and she finds difficult to understand.”

Rowlands said Patel had been highly regarded at Barclays and that the long-term consequences of her actions would be extreme.

She and her mother have now reconciled, he added, following tearful phone calls while Patel was in prison.