An undercover officer who deceived a woman into an intimate relationship was later convicted and dismissed from the police for assaulting his long-term partner, the public inquiry into undercover policing has heard.

Rob Hastings, who infiltrated pro-Palestinian and left wing protest groups for three years during his covert deployment, was convicted of assaulting his now ex-partner and mother of his three children in 2014. He was sacked by the Metropolitan police for gross misconduct as a result.

The existence of the criminal conviction was revealed at the spycops inquiry this week. Hastings was questioned about his treatment of another woman, known as Maya, whom he deceived into a year-long relationship.

After the relationship with Maya ended in 2007, he vanished from her life before reappearing seven years later. At that point he convinced Maya to break up with her then boyfriend of five years, as he said he wanted to resume their relationship and have children together.

He then had sex with Maya once, in 2015, and left before dawn, disappearingagain from her life. “The next day I visited my GP to be prescribed the morning-after pill, which I found very upsetting,” Maya said in her testimony.

On a previous occasion, she had been distressed that he may have made her pregnant and offered her no support.

Until this week, Hastings had not disclosed to her that he had had a vasectomy some time before their relationship started. He admitted he was “clearly being cruel and selfish” by not telling her.

Hastings was a member of a covert Scotland Yard unit, the Special Demonstration Squad, which spied on tens of thousands of mainly leftwing activists over four decades. He went undercover from 2004-07.

He did not disclose his real identity to Maya when they started their relationship in 2006. Maya told the inquiry she was vulnerable at the time as she had had mental health struggles and past trauma, and was “very inexperienced in sex and relationships”.

Detailing his controlling and manipulative behaviour, she described how she regularly self-harmed and felt suicidal as he often falsely accused her of infidelity and then did not speak to her. They rarely went out together as a couple.

She said: “I often felt like he was using me for sex which made me feel very negatively about myself and my body.” He told her he loved her, but only during sex, the inquiry heard.

After the relationship ended in 2007, she used heroin and crack cocaine as a way of coping with the devastation she felt, she said.

Hastings continued working for the Met after his undercover deployment and joined a counter-terrorism unit.

In 2014, he pleaded guilty to assaulting his long-term partner. They had been together for more than two decades, since he was 17. “I was suffering mentally post my [undercover] deployment. I had been off work through ill health,” he said. The sentence he received has not been disclosed.

At that time, Hastings sought to restart the relationship with Maya, but did not tell her about his criminal conviction or long-term partner. She did not discover he had been a police spy until 2019.

She said: “I feel that I was used and exploited by [Hastings] … I believe [his] behaviour toward me to have been emotionally abusive and calculated to undermine my self-esteem and sense of self-worth.”

Hastings, who disputed many aspects of Maya’s evidence or said he could not recall what had happened, accepted he had “behaved towards Maya exceedingly badly” and apologised to her. He said he felt ashamed of his treatment of her and admitted he caused her “a great deal of pain”.

He denied having used Maya for his own sexual gratification.

During his evidence, Hastings became angry with Sarah Hemingway, the inquiry’s barrister, and complained that her questions amounted to “torture”.

At one point he began to remonstrate with members of the public in the gallery before Sir John Mitting, who is heading the inquiry, issued an order for silence.

One of the core issues being examined by the inquiry is how undercover officers frequently formed intimate relationships with women while concealing their true identities. More than 50 women so far are known to have been deceived between the 1970s and 2010.