When the 50-year-old went to hospital after being knocked down on a Glasgow road, doctors discovered the life-threatening effects of years of abuse.
"I had bleeding on my brain and it had been there for a long time," said Lisa.
"The doctor said it was a timebomb. He asked if I had ever been through abuse before. He said the driver had saved me."
Lisa's abuser was her partner Steve, who used to hit her on the head because the bruises could be hidden by hair.
Steve raped, sexually assaulted and terrorised her for 20 years.
Out of fear of the consequences, and in case doctors thought she was "disgusting", Lisa did not arrange to see her GP, even though she was suffering from blinding headaches and blackouts.
The mother-of-four was put on medication after the crash in January this year, but still suffers from headaches, problems with balance and she is losing the feeling in one of her arms.
Lisa said she could not concentrate the morning she was hit by the car because of fears her abuser was watching her.
She said: "This car came from nowhere and hit me.
"I just lay there, but then I thought he was watching me so I stood up and my head was bleeding.
"Eventually I went to hospital and I asked them to check the cut on my head so I should go. That's when I had a MRI scan.
"They found a bleeding cavernoma in the left side of my brain.
"It showed I had previously had a skull fracture - I never knew I had suffered it."
Steve moved into the flat Lisa rented in the north of Glasgow when she was 28.
He was controlling from the start, but Lisa says she was unable to recognise the signs because she had suffered abuse all her life.
"I thought he was a saint, I thought he was a safety net because I was not wary of people outside," she said.
It was the people who were meant to look after Lisa who betrayed her. Her mother and grandmother were sexual abusers.
"They did anything they wanted to me," said Lisa, fighting back tears. "It started when I was five.
"My dad was working away a lot. He knew mum was cruel to me but he didn't know the extent.
"The cruelty part I could get over. It was the other part I didn't like.
"She hated me, she told me she tried to abort me and I survived. I became a recluse."
Lisa said Steve raped her "24/7".
To begin with she believed that was how relationships worked.
"I was naive," said Lisa.
Lisa was in constant agony because of Steve's experiments on her body and she felt "filthy".
As well as biting her he would assault her. "He was doing that for fun," she said.
"He said if I started crying it meant I was enjoying it so I used to pretend I wasn't crying.
"I was an object."
Lisa had her first baby two years into the relationship, but the abuse did not end.
"I never got out the house at all," she said.
There were opportunities to talk to people but Lisa could not get the words out.
"I used to stop going to the doctor's even when I was really ill because I feared they would think I was disgusting," she said.
She felt if Steve was not terrorising her then he would move on to someone else and she did not want anyone else to suffer.
The catalogue of abuse lasted for years.
Three years ago Lisa stood up to Steve for the first time in her life.
"He grabbed my chest and twisted it," said Lisa. "I said: 'Get off me.' "I froze because I faced him up."
Steve backed away from Lisa before returning with two meat cleavers.
Lisa closed her eyes and thought that being killed would put an end to all the abuse.
But she suddenly realised he would kill their children after her and so began screaming to get the attention of her eldest son, who was upstairs.
Lisa said: "He told my son he was slitting my throat. My son pinned him against the wall and said: 'Mum, run.'"
Lisa ran and did not return.
Steve was jailed for a time while Lisa sought help at support groups, including Glasgow East Women's Aid and Quarriers.
Last year she found the courage to talk to domestic abuse investigative teams about the violence she suffered. But she said they could not find enough evidence to prosecute.
She is continuing to have counselling and therapy sessions at Glasgow East Women's Aid.
"I tried to get him for all the assaults on me but they couldn't prove anything," she said. "But I was glad I told them."
Lisa recently moved into a new flat with her youngest child, but still fears Steve.
She said: "I drew the line when he tried to slit my throat in front of my kids.
"But if I ever see him and I look into his face the fear goes back into me. "I'm afraid he gets me again."
Pointing to her head Lisa said: "He's in there. I can't get him out. He is in there forever now."
l Some details and names have been changed to protect identities.