Speaking on the Monday night premiere of HLN's "Primetime Justice" with Ashleigh Banfield, Hildreth outlined in detail a relationship with Grate that she claims was rife with violence, abuse and horror. When Banfield asked her about whether she was surprised to hear of the admission he made in letters to Cleveland's WEWS news network about the killings of five women, two simple words expressed her feelings.
"Not really," she said.
Grate, the man who confessed to the deaths in letters he wrote to WEWS, is sitting in a Cleveland jail cell awaiting trial on kidnapping charges and two counts of murder.
Hildreth described in vivid detail the experiences she had living with Grate, trying to avoid his violent and abusive rages. In one instance, Hildreth claims Grate threatened her even with police at the front door. When a violent altercation drew the attention of neighbors, the police arrived, and while she stood at the door to greet them, Grate stood behind the door out of view.
"He was standing behind me with a hammer," she said. "And he told me if I told them he was there, then he was going to hit me in the head with the hammer."
During one of Grate's first stints in jail, he also reportedly threatened Hildreth by telling others in jail that he'd find her once he got out.
"A couple years after he had gotten out, he tracked down a friend of mine," she said. "He tried to get her to tell him where I lived, my phone number, things like that. She refused."
Grate's behavior during the early stage of their relationship was normal, Hildreth said, but after the two decided to move in together, she said he changed. A man whom she described as charming and handsome in the early part of their relationship soon turned into a man she described as controlling and possessive. His behavior grew more sinister and abusive.
Hildreth said Grate refused to let her go to work, answer her cell phone, or even look out the windows of her own home. For the last three years of their relationship, she said she feared for her life and constantly warned her family.
"Multiple times, I told my mother, you gotta help me get out," she said. "Or something is gonna happen."
The haunting story of Grate -- as far as Hildreth is concerned -- doesn't stop at the killings he's confessed to. She believes there's more.
"A lot of us are very circumspect about whether it's five," Banfield said at the end of the interview. "We're wondering if there are more, do you have those thoughts?"
"I do," Hildreth said. "I feel there's no way he went 10 years between his first victim and second victim."
The arrest of Grate came after a woman he's accused of kidnapping called 911 and whispered to authorities her location, while Grate slept just inches away. Upon arrival, police found the bodies of two women, Stacey Stanley and Elizabeth Griffith, in and near the home. CNN has reached out to Grate's attorneys for comment, and has not yet received a response.