Sally Challen, who was jailed for life for killing her husband in a hammer attack following decades of emotional abuse, has walked free from court after a judge announced she would not face a retrial.

Challen, 65, was sentenced at the Old Bailey in London on Friday to nine years and four months – time already served – for the manslaughter of her husband, Richard.

Speaking at a press conference afterwards, she said: “My family have served my sentence with me. They have kept me going for a long and terrible nine years. I want also to thank my friends in and out of prison who have stood by me.”

Challen said she suffered years of controlling and humiliating abuse before she killed her 61-year-old husband in August 2010.

She was jailed for life for murder after a trial at Guildford crown court in 2011. In February this year the court of appeal quashed her conviction and ordered a fresh trial in light of new evidence about her mental state at the time of the killing.

Challen, of Claygate, Surrey, admitted manslaughter but pleaded not guilty to murder. She was due to face a new trial on 1 July, but at a hearing before Mr Justice Edis at the Old Bailey on Friday the prosecution said the crown accepted her plea to the lesser charge.

“Allowing full credit of one-third because it has always been your case that you killed him by reasons of diminished responsibility, that means you have already served an equivalent sentence and are therefore entitled by law to be released at once,” Edis said.

Challen’s son David tweeted: “As a family we are overjoyed at today’s verdict and that it has brought an end to the suffering we have endured together for the past nine years. Our story has become the landmark case society needs to recognise the true severity of coercive control.”

In a victim impact statement read to the court, Challen’s other son, James, said: “We have lost a father and we do not seek to justify our mother’s actions.” He said his mother “does not deserve to be punished further”.

Challen walked free from court to applause from supporters. Sitting next to her sons at the packed press conference, she said: “Many other women who are victims of abuse as I was are in prison today serving life sentences. They should not be serving sentences for murder but for manslaughter.”

Sally Challen and her son David at the press conference. Photograph: Yui Mok/PA

She added: “I still love Richard and miss him dreadfully and wish that none of this had happened. I’m just so happy I can begin to live my life again. I have had major ups and major downs. Without the support of my family and my endless telephone calls to them at inappropriate times, I don’t know how I would have coped.

“It has been a really long road and at one point I didn’t see any light at the end of it. It’s wonderful to be free and to be able to see my sons. I’m so grateful to them.”

Challen said she hoped the justice system would take abuse more seriously. “I met many women in prison who shouldn’t be there. Getting an appeal is very difficult. I was turned down on the first attempt. The justice system needs to listen,” she said.

“A lot of the problem is that women don’t know they’re in a relationship of coercive control. It’s family, friends and relatives who do see it. Somehow they have to speak to that person and convince them to leave. They don’t seem to be able to break that tie. It’s a very strong tie and the women are very vulnerable.”

She said schools should teach children about coercive control, as boys as well as girls suffered from it. “They’re damaged and it’s damage done to them for the rest of their lives. Teachers also should be aware and look around their classrooms and make the children aware of what could happen.”

David Challen said: “There’s no shame in what we’ve gone through. This has exemplified how the criminal justice system continues to discriminate against women who kill. We have sought justice and understanding.”

The prospect of a retrial was seen as a key test of new laws on domestic abuse and coercive control. The family say Richard Challen subjected his wife to decades of psychological abuse, which is referred to as coercive control under laws introduced in 2015.

Richard Challen was unfaithful throughout the marriage and frequently visited brothels. Sally Challen moved out of the family home in 2009 but was said to still be emotionally dependent on her husband. When she discovered he had contacted another woman, she hit him more than 20 times with a hammer.

The appeal court was told she had two mental disorders at the time of the killing, and that her condition was likely to have been made worse by the coercive control.

Justice for Women said it was fighting 10 other similar cases. Harriet Wistrich, the organisation’s founder, said the CPS had a commitment and obligation to understand domestic violence, “but you don’t see it in practice. You see them going ahead as though they just want to win these cases. I would like to see them honour their commitments.”

Wistrich said her organisation had written to the director of public prosecutions about the case and was yet to receive a response.

The shadow equalities minister, Carolyn Harris, said Challen’s was a “landmark case for victims of coercive control”.