Technology is increasingly being used by domestic abusers to trap, control or hunt down their victims, Refuge has told the Victoria Derbyshire programme.
"It made me feel sick to the pit of my stomach - am I going to be able to break free from this relationship fully?" says "Ellen", who was stalked by her ex-husband using their family computer.
"It was like you can't get away from him."
She was subjected to coercive control during her entire 20-year marriage. He would regularly "kick off" and humiliate her in front of friends.
"It was just 20-odd years of this horrible realisation of what hell I was living," she says.
Eventually, she left for a secure refuge.
Later, she arranged to meet a friend and put the date and time into her Gmail diary on her computer - but not the location.
When Ellen approached her friend, she saw her smile, but then the friend's face suddenly dropped.
"He [the ex] just jumped out at me," she says. "Like suddenly he was there in my face, and it scared the life out of me.
"I was just so shocked and horrified. He said, 'found you, got you'."
Ellen and her friend managed to get away. Later, she realised he had accessed the information in her Gmail account and diary.
She thinks either he had followed her friend from her home, as he knew where she lived. Or, when she signed into Gmail from her new location, it could have created an alert to say she had logged in from a different location.
"I'd moved to a completely new town, miles and miles away. I had no connection to this place, there was no reason he should know where I was."
He is no longer tracking her.
'Like a thriller'
Refuge supports 6,500 women each day. Around 95% of all these domestic abuse cases involve such abuse, research it conducted with Google suggests.
The charity has launched a tech abuse service in partnership with Google to help support these women to use technology safely and take back control of their lives.
Louise Ashwell, a caseworker from its tech abuse unit, helps people who think their partners are using technology to monitor them.
"We had loads of women who were telling us, 'I'm going to the police, I'm going to these agencies and people think I'm crazy,'" she says. "It sounds like something out of a thriller or a crime film, he keeps turning up."
The abuse can get very sinister - with people even using GPS trackers to monitor ex-partners.
"The kids would come back from having seen their parent and those little location trackers might have been sewed into the lining of their coat, they might have been sewn into the lining of a toy, their teddy bears," Ms Ashwell says. "It's happening and we can't pretend it's not."
Their advice includes how to create passwords which are difficult to guess.
But the abuse often starts during a relationship.
One woman, Euleen Hope, said her ex-partner used their smart TV to spy on her.
She realised this when he said he had known when she had decided not to answer a call via Skype which was loaded onto the TV. He said he had seen her sitting on the sofa as he rang.
"From the settings he'd put on there he could watch and spy," she says.
He also used an iPad to watch her in the kitchen.
Euleen's partner of 10 years was was also physically violent, and was eventually sent to prison for attacking her.
It is a pattern Refuge has identified. Their database shows that 68% of all tech abuse cases also involved physical violence.
"Very disturbingly, what we are seeing is, the victims experiencing tech abuse are at the highest risk of being seriously physically harmed or even killed," says Jane Keeper of Refuge.
Both Ellen and Euleen successfully escaped their relationships.
"I only really figured about this cycle of abuse when I ended up in a refuge - then came the journey to my new life," says Ellen.