"I think about her every single day," Carey says in a sneak peek of his first in-depth television interview, airing Saturday.
Almost two years ago, Harwick died after falling off the third-story balcony of her apartment in the Hollywood Hills. At the time, reports indicated that police had been called to the residence by Harwick's roommate, who told authorities she was being assaulted in the apartment. Her ex-boyfriend, Gareth Pursehouse, was later arrested and charged with murder. He has pleaded not guilty.
"When I heard that she got murdered, right away I thought, 'Oh, it's got to be that guy,'" Carey says in the clip.
Harwick and Pursehouse dated years ago, before her engagement to Carey. Harwick had taken out restraining orders against him in 2011 and 2012, claiming he attacked her multiple times and alleging he threw her out of a vehicle on the side of the freeway.
In the sit-down, Carey also recalls his final texts with his ex, saying, "Valentine's Day was a Friday. I got a text from her on Thursday. [She] said, 'Hey, I know we haven't talked in a while, but I've been doing a lot of thinking about, you know, forgiveness, and I would love to get together with you and talk.' And I said, 'Yeah, I would love to do that. I love you.'"
"I say that to a lot of people," he continues, "but, I mean it. And I was really happy, like, 'Oh, it'd be great to see her again.'"
Carey and Harwick met in 2017 at a Hollywood party, where she was moonlighting as a bartender to pay for school. She was a practicing therapist with a master's and a Ph.D. They then got engaged before calling it off in late 2018, with friends saying the split was amicable.
"Our first date we went to Disneyland," Carey recalls in CBS News' accompanying piece, sharing how he instantly fell for her. "I said, 'Wow, I met this great girl. Her name's Amie. She's a Ph.D. and she's a therapist.' And I said, 'If this keeps going the way it's going, I'm going to marry her.' I just said it right out, and I'd only known her for, like, a couple weeks," Carey reflects. "I just knew that she was special."
Carey notes that his fame was one of the things that led to their breakup, claiming Harwick would tell him, "I wish you weren't famous." They spent some time in therapy to try and make things work.
"I feel like a widower, you know, in a lot of ways, because I wanted to marry her, and then we had this horrible breakup," Carey says. "And then before I could talk to her again, somebody killed her."
He adds that the solace he gets is knowing that Harwick loved him. "That's the big solace I get from it, is that she loved me and held me in a dear place in her heart," he adds.
Carey's full interview will air Saturday, Feb. 12 at 10 p.m. on CBS and stream on Paramount+.