A 73-year-old woman who beat her husband to death with a wooden pole after suffering years of abuse has been cleared of murder.

Packiam Ramanathan attacked Kanagusabi Ramanathan, 76, as he lay in his bed, the Old Bailey heard. She denied murder but pleaded guilty to manslaughter, citing his bullying and abusive behaviour during their 35-year marriage.

The Old Bailey heard that the couple had an arranged marriage in 1983 and fled Sri Lanka during the country’s civil war.

On 21 September last year paramedics found Kanagusabi Ramanathan, a former shopkeeper who used a wheelchair, dead in his bedroom after his wife told her neighbour she had hit him.

He was found to have serious head injuries and multiple wounds to the body and neck, and other injuries to his arms and hands from trying to fend off the blows. A blood-stained wooden stick was found in a cupboard in the hall of the couple’s flat in Newham, east London.

Sally O’Neill QC, prosecuting, said there had been arguments about money and the defendant had become angry at finding out her husband had written to Sri Lankan police accusing her brother of fraud and theft.

She said: “There is no dispute that the person who used that stick to cause those injuries which killed him was his wife, and the prosecution case is that there can be also no doubt that she did so intending, at the least, to cause him really serious harm and that he was unlawfully killed as a result – that is, that she murdered him.

“The prosecution case is that this was a brutal and sustained attack by this defendant on a disabled and defenceless elderly man whilst he was lying in his bed and that the attack was probably motivated by anger.”

Giving evidence, the defendant claimed she had lost of control after suffering years of bullying and abusive behaviour by her husband. She alleged he had thrown sticks at her and subjected her to years of verbal abuse.

Recalling the killing, Ramanathan told jurors: “It was like I was in a trance. I hit him. I do not know. I did not know what I was doing. I could not feel this. I remember him saying ‘don’t hit me’. I remember I hit him.

“I lost control at that time. I did not plan anything. I’m not a person who would do such a thing. I don’t know how I did it. For me, I still feel like somebody else did it.”

Stephen Kamlish QC, defending, suggested that if Ramanathan had wanted to kill her diabetic husband, she could have simply given him a bigger dose of insulin and “no one would have known”.

He said: “Him dying in the night would not have been unexpected. It’s what she could have done. The fact it was done in the way it was – with a stick – means there was no planning. The fact it was done with such severity is evidence of loss of control.

“She is frail, she is slight, she is getting on for anorexic weight. It’s hard to beat someone to death with a stick when you are that size.”

Kamlish urged jurors to acquit her of murder, saying: “After the hell of this trial, the hell of 36 years of abuse, you can show what you think of this prosecution and do the right thing by coming to a very fast verdict.”

The jury deliberated for half an hour to find Ramanathan not guilty of murder.