No one ever really knows what goes on behind closed doors. Few friends and neighbours were aware of the litany of violence, alcoholism and suicide attempts that marred 32 years of dysfunctional marriage between Anne and Pat Burke. It only ended when she struck him 23 times on the head with a hammer while he slept, extinguishing his life and – in many ways – liberating her own.

Anne Burke (56), of Ballybrittas in Co Laois, admitted hitting her husband Pat Burke (55) over the head with a hammer while he slept, but denied murdering him at their home on 19 August 2007.

After listening to evidence over two days that detailed the pitiful existence that was Anne Burke's life at the hands of her domineering husband, a jury found her not guilty of murder but guilty of her husband's manslaughter on the grounds of diminished responsibility. Anne had wanted to leave her husband but could not see a way out. A depressive disorder paralysed the middle-aged woman into remaining in a marriage that was fraught with abuse.

Even before they married, Pat began beating his wife. But Anne didn't find that unusual; she'd watched her own father beat her mother relentlessly as she grew up. But after they wed, the violence intensified in the household where they were soon raising four young children.

As the years went on, the abuse took its toll. Eventually, Anne began to hit her husband back. She also turned to alcohol to give her strength to stand up to his drunken attacks and numb the pain. On a few of occasions, including six days before she killed her husband and immediately after she bludgeoned him to death, she tried to take her own life, believing her children would be better off without her.

The beatings were often out doled out in front of their children, two boys and two girls, who also suffered violence at the hands of their father. He raped his wife when she rejected his sexual advances, she later told psychiatrists. He pointed a shotgun and threatened to murder her and dump her body in the Dublin mountains. Once, when she was pregnant with their son, he kicked her in the stomach. Yet she did not have the mental strength to leave this man or force him out of their home. In a way, she still loved him. "As I said, we were always fighting," she told gardaí after the killing. "But there was something there. We stayed together."

Linda Burke gave evidence of standing in her pyjamas as a toddler with her older brother at the top of the stairs looking down at her father, who was brandishing a loaded shotgun and shouting that he would blow her mother's head off. She told the court that her father also often beat her, even throwing her across the room when she had difficulty learning how to tell the time. The fighting between her parents was constant. When she was 13, she recalled her father attacking her mother with a sweeping brush, splitting her forehead open.

Gardaí were aware of the violence – they had been called to the house many times. Anne had a barring order out against her husband but she let him back into the home because "he threatened to shoot all of us, and himself".

Six days before his death, Pat Burke phoned gardaí. They found Anne locked in the bathroom having cut her wrists. She was admitted to a psychiatric ward but released two days later. "If you don't come out today, you need not bother your arse coming out at all," her husband told her, she said. When she returned home, he said he was ashamed of her. The arguing began in earnest, continuing on and off for days until, finally, it culminated in his violent killing.

On 19 August 2007, Pat Burke arrived home in the small hours of the morning drunk and abusive. The couple rowed for several hours before he went upstairs to bed. After having several drinks, Anne followed him upstairs, picked up the hammer that was lying in the bedroom and hit him over the head 23 times, shattering his skull. She remembers hitting him a couple of times with the hammer but not over 20 times. "I knew when I saw it that I did it… I don't know why I did it. It was a haze... it was like someone else was doing it," she told gardaí. She wiped the blood from her husband's face and the walls and covered him with a blanket before writing a suicide note to her four children. "I just knew I didn't want to live," she told gardaí.

But Anne did live. Her son found her in the hallway and brought her into the bedroom to bandage her arms. There he discovered his father's body on the ground.

After hearing from two psychiatrists that Anne Burke was suffering from a mental disorder that caused her to have a diminished ability to think clearly or concentrate, the jury took just 30 minutes to return its verdict on Thursday.

Her daughter Linda, who had been at her side throughout the trial along with her brother Peter, held her mother's hand and broke down in tears as the verdict was delivered.

Anne Burke was granted bail and will be sentenced on 25 January.