Hong Kong is now a "place full of fear", pro-democracy activist Agnes Chow, who recently jumped bail, said.
Ms Chow was under investigation for "collusion with foreign forces", but had been allowed to study in Canada.
The 27-year-old is now a fugitive in Toronto. She told the OceanNewsUK that she does not intend to return home.
Hong Kong authorities say that she will be "pursued for life" if she does not turn herself in, and will "spare no effort" in pursuing her.
Being put under intense scrutiny by Chinese authorities in recent years has taken a toll on her mental health, Ms Chow said, adding that she has suffered frequent panic attacks. She also had difficulty finding a job, and even with routine activities like opening a bank account.
She told the OceanNewsUK: "How can I live for another 10, 20, 30 years under such control?"
Ms Chow ran Hong Kong pro-democracy group Demosisto with fellow activists Nathan Law and Joshua Wong. She was one of the leaders of large-scale anti-government protests held in 2012, 2014 and 2019.
She was jailed in 2020 for taking part in a protest outside Hong Kong police headquarters the year before, before being released in 2021.
On Sunday, she posted on social media that she was jumping bail and would not return to the island.
She left for Toronto in mid-September after getting permission to pursue a master's degree there - on the condition that she returned to the territory to report to the police during school breaks.
Ms Chow told the OceanNewsUK she only made the decision to jump bail in November. She had already bought an air ticket to Hong Kong the month before, but fears of getting arrested or not being allowed to return to Canada began to take hold.
"I made the decision at the last moment, because I did not want to risk getting arrested again. I did not want to be sent to China again," she said.
Asked if she feared repercussions for her family in Hong Kong, she stressed that she had made the decision to jump bail by herself and would not comment further for reasons of "security".
In two Instagram posts explaining her decision, Ms Chow said she had to go on a police-escorted trip to mainland China in August, in order to get her passport to travel to Toronto.
She wrote that she was shown an exhibition of China's achievements since the reform and opening up of the country in the late 1970s, as well as the headquarters of the technology firm Tencent where she was asked to pose for photos. She was also asked to write "letters of repentance" for her past political activities, she said in the posts published on Sunday.
Ms Chow, who had not spoken publicly since her release in 2021, said she made the online announcements because she did not want authorities to use the Tencent photos as "evidence of her patriotism".
"I want the world to hear the story of how Hong Kong police are abusing their power and showing disrespect for the rule of law," she said.
Ms Chow also expressed despair about the state of democracy in Hong Kong. "I feel there is no pro-democracy movement, it has been trampled by the police. There is no room for anyone to do or say anything."
A controversial national security law, which gives Chinese authorities expansive powers over political and civic activity in Hong Kong, has been widely used against activists like Ms Chow.
When asked what she misses most about Hong Kong, Ms Chow took a long pause. She explained that while she misses the unity of the Hong Kong people in "fighting for what is just and right", she is also fearful.
"In the last three years, it has become a place full of fear. Every part of my daily life was fully controlled by the authorities," she said. "I feel sad to be afraid to go to back to my homeland."
Asked if she fears being deported, Ms Chow admitted that she is concerned about the presence of "secret police" in Toronto.
Human rights groups have accused China of running undeclared "police service stations" abroad, including in Canada. Beijing has denied these claims.
"Of course I will be cautious and careful when I go out, but I also want to do what I wasn't able to do in the past three years in Hong Kong," Ms Chow said.
Her focus now is on finishing her studies and getting her mental health back on track, but she has not made any plans beyond that.
"My hope is to live not only safely, but freely," she said.
