The Crown says Ford, 44, murdered Mr Marshall. She has pleaded not guilty to murder but admitted stabbing her 45-year-old partner.
Her lawyers argue she was acting in self-defence, which is a complete defence.
If the jurors find Ford acted in self-defence and that the force she used was reasonable then they may acquit her.
If they determine she acted in self-defence but used excessive force, then they may find her guilty of manslaughter.
A witness has told the jury that he was delivering circulars on the day of the killing and heard yelling and swearing before seeing Mr Marshall punch Ford in the face and bash her head against the front door frame three times.
Ford told the court yesterday that the abuse continued as Mr Marshall dragged her inside the house by her hair.
She said Mr Marshall put a hand over her mouth to stop her calling out to neighbours. She bit his finger and he pushed her to the ground.
"Gary was kicking me. I was lying on the ground. I curled up, protecting my head in the fetal position so he couldn't kick my ribs because I was winded."
She said she threatened to call the police but Mr Marshall grabbed her cell phone and snapped it in half.
"He said: 'Who you going to call now, you b****?'."
Ford said Marshall put his hands around her throat and said: "I'll f***ing kill you, you b****."
He then slammed her head into the kitchen bench before she reached for a kitchen knife.
"I picked up the knife. He pulled me back up."
Ford then made an action of lunging forward with the knife.
"That was it. I threw the knife across the kitchen."
She burst into tears as she described seeing Marshall take a few steps back and fall into a pool of blood on the floor.
She said she phoned the ambulance before grabbing two towels and ice and applying pressure to the wound.
Under cross-examination from Crown prosecutor Mark Davies, Ford admitted she had lied to police on the day of the killing when she told them Mr Marshall had killed himself.
"I was in shock at the time and had been through a traumatic experience."
She said she was not thinking straight and had concussion.
Mr Davies asked: "But now everything is coming back with perfect clarity?
Ford responded: "No, not with perfect clarity but I'm not in shock. I haven't just had the hiding of my life."
She was also questioned about exactly when and where she received a bump on her head and a cut behind her ear.
Ford said she was not sure exactly when Mr Marshall had caused the lump on her head.
The trial is due to finish at the end of this week.
