Sent thousands of abusive text messages, ousted from her main position in government and told she will be sent to prison, it's been a rough week for Filipino Sen. Leila de Lima.

"It's been hell," she says.

De Lima is the Philippines' fiercest critic of the country's new strongman president Rodrigo Duterte, and she says his "personal vendetta" has her scared for her safety.

Duterte, referred to in the media as "Duterte Harry," has implemented an internationally condemned war on drugs in which more than 3,400 alleged drug dealers and users have been killed. But there is also a battle at the heart of government between Duterte and de Lima, stemming largely from de Lima's opposition to the way the war on drugs has been carried out.

Filipino demonstrators mimic an extrajudicial killing crime scene as police officers stand guard during a protest in front of the Philippine National Police (PNP) headquarters in Camp Crame, Quezon City, northeast of Manila, on Aug. 26, 2016.

'These are crimes'

In August, as chair of the Senate committee on justice and human rights, she initiated an inquiry into the spate of killings that has taken place since Duterte assumed office at the end of June.

She told CBC News: "When is the proper time to tell the truth? When is the proper time to put him [Duterte] to task for these crimes? These are crimes, because this is murder — extrajudicial killings are murder."

Duterte's office and the police deny any wrongdoing. The police say that most of the killings have been carried out by vigilantes, hit men and drug gangs, whilst the approximately 1,500 killings at the hands of police were carried out in "self-defence."

A week after de Lima began the inquiry into the drug war killings, Duterte claimed the senator was having an affair with her married driver. He then claimed money was being given to de Lima by drug lords imprisoned in the New Bilibid prison — the Philippines' main penitentiary — to fund her senatorial campaign.

It is because I dared speak, I dared question and oppose the methods being employed in this war on drugs. - Filipino Sen. Leila de Lima

"It is so absurd it is almost surreal," she said. "It is because I dared speak, I dared question and oppose the methods being employed in this war on drugs."

Two government inquiries have since served as courts for the accusations from both sides. On one side, de Lima's Senate committee hearings, and on the other an inquiry into the drug trade at the New Bilibid prison.

The hearings into the killings took a dramatic turn last week with the testimony of Edgar Matobato, a self-confessed former assassin from the Davao Death Squad vigilante group that has allegedly killed thousands of criminals in the city of Davao.

Matobato said Duterte, who spent more than 20 years as mayor of Davao, had ordered the killings of criminals and his opponents by the group. Matobato also claimed that Duterte had personally killed a justice department official with an Uzi submachine gun and had even ordered a (failed) assassination attempt on de Lima in 2009.

Duterte's office has denied all the claims and says there are inconsistencies in Matobato's evidence. The president has said he does not know Matobato.

Philippine President Rodrigo Duterte has implemented an internationally condemned war on drugs in which more than 3,400 alleged drug dealers and users have been killed since he assumed office at the end of June. (Manman Dejeto/AFP/Getty Images)

One week later, de Lima was ousted from her position as chair of the Senate committee after Manny Pacquiao, the boxing superstar turned Filipino senator and close ally of Duterte, tabled a motion saying she was biased.

De Lima's removal is "a craven attempt to derail accountability for the appalling death toll from President Duterte's abusive 'war on drugs,'" said Phelim Kine, deputy Asia director at Human Rights Watch.

"The Senate is imperiling the Philippine public by covering up allegations of state-sanctioned murder rather than exposing them."

The inquiry into New Bilibid prison has heard from 10 drug convicts who linked de Lima to the drug trade in the prison.

De Lima questions the motives of these witnesses after, as justice secretary in 2014, she raided the prisons to end the "luxury" lifestyle of incarcerated drug lords.

'I was hounded'

During the inquiry, de Lima's address and mobile phone number were also publicly released.

"That was a blatant violation of my rights," she said. "I was hounded — almost 2,000 threatening and harassing text messages, very, very foul, the vilest language, calling me names and all that.

She said she is no longer sleeping at home, instead "taking temporary refuge in other areas and in other places."

She adds: "I am scared, of course. I am more than scared."

Duterte is not known for holding his tongue, having called U.S. President Barack Obama a "son of a bitch" (or "son of a whore," according to some translations) and UN Secretary-General Ban Ki-moon a "devil."

He has accused de Lima of being an "immoral woman" and said, "If I was Senator de Lima, I would hang myself." He has said that charges will be filed against de Lima and that she will end up in prison.

De Lima said: "His whole attitude of not being open and forgiving to any opposition, any dissent, any contrary voice is very revealing…. If you stifle liberties, if you stifle dissent, if you make a mockery of our bill of rights, isn't it clear? Isn't there creeping authoritarianism?"

And though she says friends have asked why she does not stop her campaign, she has no intention of giving up.

"I have a choice," she said. "Surrendering everything and just keeping quiet and probably resigning from this post [as senator] and just waiting for all of those cases to be filed against me — or fight.

"I choose to fight, for as long as I can, for as long as I will be allowed to do so, for as long as I am alive."