Alison Lewis arrives at Swansea Crown Court

Mrs Lewis - who was once a prime suspect for the murders - was asked point blank by prosecutor Patrick Harrington QC: "Did you have anything to do with the murder of your lover?" She replied "No, I did not".

David Morris, 39, a scrap metal dealer from Craig Cefn Parc in the Swansea Valley, denies murdering Mrs Power, 34, her two children Katie 10, and Emily, eight, and their invalid grandmother Doris Dawson, who was 80.

The family had been bludgeoned to death with an iron pole, and fires were also lit around the house.

In an emotionally charged atmosphere at Swansea Crown Court, Mrs Lewis, from Pontypridd, was asked the same question about the murders of Katie, Emily and Doris Dawson.

She wept while she repeatedly denied having anything to do with the killings.

David Morris denies four counts of murder

"I loved them all", she said.

Mrs Lewis has described how she began an intimate and passionate relationship with Mrs Powers, only two weeks after the couple met.

On the second day of cross-examination by Peter Rouch QC, defending, she said that she had been overcome by a "wave of grief" after learning of the killings.

Mrs Lewis had revealed that she kept her affair with Mrs Power secret from her police sergeant husband, Stephen Lewis, which was why she went "berserk" twice at the psychiatric unit as a result of her emotional pain, and it taking eight nursing staff to restrain her.

"When I found out that Mandy and the children and her mother were dead I found it very difficult to deal with - how do you deal with that?

"I had no one to talk to and I reacted badly to the news that I'd been given.

The family's burned-out house in Kelvin Road

"I was in so much pain, the pain was tremendous. It was like waves of grief were coming over me all the time."

Mrs Lewis finished her testimony by accusing South Wales police of putting her though "hell" during four days of questioning when she and her husband were arrested - but later released without charge - as part of the inquiry.

She said: "As far as I am concerned South Wales Police tortured me with my grief.

"Sexual adventurer"

"They tried to break me. The reason they did not was that I was telling the truth." Mrs Lewis left the court sobbing.

On Tuesday two witnesses told the murder trial they saw David Morris wearing a gold necklace similar to one found at the scene of the murders.

The jury has already been told that Mr Morris admitted the necklace was "probably" his days before the case opened last month.

The case, which is in its second week, has already heard that the family were beaten to death with an iron bar with Mr Harrington describing the deaths as a "massacre".

Details of Mrs Power's private life have also emerged - since her divorce, she had become something of a "sexual adventurer".

The trial at Swansea Crown Court is continuing - minus one of its panel of jurors who suffered a stroke at the weekend.