Those were among the revelations Melody Granadillo, 23, made during an interview on ABC's "20/20" last week, as she shared details about her romantic involvement with van der Sloot. The couple first met in 2003 and dated for about seven months in Aruba when they were 17.
Granadillo told reporter Chris Cuomo that she initially thought van der Sloot -- whom she described as her first love -- was "romantic ... playful [and] very honest."
"We could sit and talk for hours," Granadillo said. "We liked looking into each other's eyes."
But all that changed, Granadillo said, when van der Sloot started lying to her and she discovered he was cheating.
"He would lie for no apparent reason at all ... and if you caught him at it ... he would double down and be even more serious about the story," she said.
Even after their breakup, however, the couple remained close, and Granadillo said they even kept in touch throughout the Natalee Holloway case.
Holloway, an 18-year-old Alabama woman, vanished on a trip to Aruba in 2005. She was last seen leaving a nightclub with van der Sloot, who was then living in Aruba. Her body has never been found.
In the past, van der Sloot has made multiple confessions regarding Holloway's disappearance, and was recently accused of trying to extort money from her family in exchange for details about her death and the location of her body.
Granadillo said she did not initially believe van der Sloot was involved in Holloway's disappearance, but later became concerned when she saw the way he reacted when questioned about it. His responses, she said, reminded her of the lies he told when she confronted him about cheating on her.
"I thought, 'Oh my God, here we go again,'" Granadillo said. "I thought he probably panicked and did what he always does -- he covered up."
Granadillo said van der Sloot texted her on the same day he met 21-year-old Stephany Flores in Peru, asking for $200. Suspecting he would use the money to gamble, Granadillo declined the request. That was the last time she heard from him -- but she soon saw his face everywhere, in photos accompanying news stories worldwide after he was charged with Flores' murder.
Flores, a Peruvian business student, was found dead in van der Sloot's hotel room on June 2, setting off a police manhunt that ended with the arrest of the 22-year-old Dutchman in Chile the following day. He was subsequently extradited to Peru and charged with first-degree murder and theft. If convicted, he faces 15 to 35 years in prison.
Seeing Flores' picture in the media was a shock to Granadillo, who says they look eerily alike. "It could have been me," she said.
Despite all that has happened, Granadillo said she does not regret her relationship with van der Sloot. While it has been difficult "to see him change the way he did and become the person he has," she said, "I know him differently. He was a caring person."
Those old feelings, however, do not make her blind to the reality of the situation. "I did not think [in the past] he was violent, but ... as the time goes by, now especially, I think he was," Granadillo said.
While Granadillo has lost touch with van der Sloot since his arrest, she remains in contact with his mother. Anita van der Sloot reportedly sent Granadillo an e-mail last week in which she said her son is "not a murderer" and suggested that he is being set up.
"He is not the monster they like the world to see," the e-mail reads. "He is traumatized, depressed and has an addiction. He is not a murderer. It stinks and feels like a big trap set up for him."
The Dutchman's mother also broke her silence Sunday, telling the Dutch newspaper De Telegraaf he was "sick in his head, but he didn't want any help."
She maintained that her son had not killed Holloway, but seemed to waver on whether he was guilty of Flores' murder. "If he killed Stephany, he'll have to pay the price," she said. "I won't visit him in his cell. I cannot embrace him."
Meanwhile, van der Sloot has retracted his alleged confession in Flores' murder, telling a journalist from De Telegraaf that Peruvian police "tricked" him into admitting his guilt.
"I was scared and confused during the interrogation and wanted to leave," van der Sloot said. "In my blind panic, I signed everything but didn't know what it said."
The retraction comes as little surprise to experts who have been following the case. In fact, forensic consultant Dr. Park Dietz predicted it in an interview with AOL News earlier this month.
"A strategy that he apparently has learned ... is that if you mistakenly tell the truth, you might be able to diminish the consequences by radically changing your story and claiming you were lying before," the founder of Park Dietz and Associates in Newport Beach, Calif., told AOL News. "You can then do it again and again.
"And if you tell enough different versions, no one will know what is true, and they won't be able to rely on any confession you've made," Dietz said.
Van der Sloot, who is being held in a maximum-security prison in Peru, is scheduled to be interrogated today by Lima Fourth Criminal Court Judge Carlos Morales. The judge will review the alleged confession and other evidence in the case to determine whether van der Sloot will stand trial for Flores' murder.