A woman has revealed how an undercover police officer formed a long-term intimate relationship with her without disclosing his real identity, vanished from her life – and then reappeared seven years later.

When the officer came back, she says, he persuaded her to break up with her then boyfriend of five years, saying he wanted to resume their relationship and have children together.

He then slept with her for a single night, disappearing from her life again before dawn the next morning without explanation. She feared he had made her pregnant as he had not wanted to use a condom, and so she had to get the morning-after pill.

The woman, known as Maya, has described how the officer, who used the fake name Rob Harrison, tormented her during their relationship with what she felt was controlling and coercive behaviour, such as regularly accusing her – falsely – of infidelity via text messages and then not speaking to her.

She said his abusive behaviour drove her to self-harm and to use heroin. “Sometimes I hope that he really loved me. Other times I think, ‘oh, you sick bastard’,” she said.

Maya had started the one-year relationship with “Harrison” in 2006, while he was infiltrating pro-Palestinian campaigners.

His conduct is to be examined by a judge-led public inquiry, which is looking at how about 139 undercover officers spied on more than 1,000 predominantly leftwing groups between 1968 and at least 2010. One of the key issues for the inquiry is how the police spies frequently formed intimate relationships with women, often lasting years, without telling them they were undercover officers infiltrating political groups. Some fathered children during their deployments.

Harrison declined to comment. His lawyer said the officer had “provided a detailed statement to the inquiry and is co-operating with the inquiry” and believed that was “the correct venue” to deal with the matter.

Maya found out only in 2019 that Harrison was a police officer, which caused her to experience periods of suicidal feelings and further self-harm.

In a three-year covert deployment that started in 2004, Harrison infiltrated the International Solidarity Movement, a group supporting Palestinians, and anti-war campaigns. As part of his fake persona, he said he had a job as a sound engineer in south London and was a DJ called Boogie Knight.

What Maya calls her “shittiest relationship” started in May 2006. She was not politically active – but lived next door to campaigners in south London and socialised with them.

At a fundraising concert, Harrison made a sudden move on her, she said, asking out of the blue – “‘So you want to kiss me now?’ And I’m like, what?. I was shocked and flattered at the same time.” She was in her 20s, younger than Harrison, and inexperienced in relationships.

During their relationship, she said, he saw her only when he visited her home at night, and they would rarely go out as a couple. “I pretty much isolated myself from people who were very good friends,” she said.

She said she wondered “how much was he really using me to spy on people, versus how much was he using me just for sex, because, when he would come round, it would be 11 at night, one in the morning, these kind of crazy hours.

“I was always getting text messages … accusing me of running off with somebody else … he just wouldn’t reply to any of my calls. And so that would make me more frantic.”

She added: “I indulged in a lot of self-harm. And then I would tell him afterwards. And then he [would say] ‘I don’t want you to hurt yourself’. And then we’re back together. Then he comes up with more accusations. And it was just like this cycle.

“I would have my phone constantly on, because he’d be sending a text message at one in the morning, saying, ‘look out the window’. And I look out the window, and there he is outside the window, and then he comes into the house.” She added that she feared that if she did not answer, he would accuse her of sleeping with another man.

“It just made me constantly on anxiety mode for many months because I was even too afraid to go to sleep in case he had texted,” she said.

She added: “He led me to believe that his outbursts of unreasonable behaviour were due to past trauma”.

Around April 2007, Harrison told Maya he had to move to Durham to look after his mother, who was dying of cancer. She had not met his family as he had said he had little contact with them.

She was devastated by his abrupt departure. “I didn’t know how to cope with that, and I turned to heroin. I never even smoked cigarettes. I didn’t smoke weed. I just went straight to class A.” She took heroin for three months.

For several years, they did not meet but exchanged intermittent emails. She recalls one email “saying ‘we should meet up and then I can tell you all about it’. And then he said, ‘then you can fuck me’. I just felt so offended.”

In August 2014, the officer got back in touch with Maya, still using the fake name of Harrison. He claimed to live nearby and to be working as a corporate consultant.

“He told me that in all the years that he’d been away, he’d never been with another woman, that he couldn’t stop thinking of me, that he was so sorry he had to go away, that he had to bury his mum alone, and that if there was any chance we could get back together.”

Maya said he told her he wanted to have children together. At the time she had been living with her boyfriend, but she broke up with him after Harrison persuaded her over several months to resume their relationship.

In February 2015, she and Harrison again slept together. “He had sex with me, and then I never saw him again. He left in the early hours of the morning … maybe 4am, 5am … before dawn.”

Harrison had told her he did not want to use a condom. “I just was so scared that I could be pregnant, so I had to go and get an emergency morning-after pill. I still think to this day, if I had totally trusted him, if I was ready to have family, if I didn’t get that emergency pill, I could have had his baby by now, but that he didn’t even communicate with me at all after that,” she said.

He had returned to her a few months after Theresa May, the then home secretary, had commissioned the public inquiry in March 2014, following a series of revelations about the misconduct of the undercover officers.

She does not know why he returned to her and said he wanted to marry her. It is not known when he had left the police.

Maya last heard from Harrison in 2016, when he sent her a cryptic email to say he thought he had seen her at a train station, adding: “Then I remembered the clouds and the storm, and they are coming. Yes, they are coming.”