In a letter penned to the late actress on Instagram, the dance pro looked back at their ups and downs over the years.
"My dearest Kirstie," he began in the Dec. 6 Instagram post. "We haven't spoken lately and I'll tell you everything when I finally see you, but for now I want to say that I love you very much and I wish you the most peaceful rest."
Chmerkovskiy and Alley competed on two seasons of Dancing With the Stars together, coming in second place on season 12 in 2011 and then being the seventh eliminated pair after returning for season 15's All-Stars edition in 2012. However, they appeared to grow apart after the show, with the drama playing out on social media and in interviews.
"You were one of the most unique people I have ever met and easily one of the brightest moments of my personal and professional life," Chmerkovskiy added. "Some of our relationship is heavily documented. Most of it is known to select few. All of it was like a wild rollercoaster."
Still, the dancer will never forget the Cheers alum.
"From Maude to DJ Lil Buttercup you were always all in for life," he wrote. "As I'm typing this, memories of our time together rush to my head, I remember how absolutely wild you were and I start to tear up. Something you'd absolutely hate. And now I can't help but smile because I remembered exactly what you wanted me to say at your funeral. Don't think I can do it here…"
And Alley will always have a place in Chmerkovskiy's heart. "I thought you'd be around forever," he concluded. "I wish we spoke often. Thank you for everything. I love you Kirstie Alley. RIP."
During a 2014 episode of Watch What Happens Live With Andy Cohen, Chmerkovskiy said he and Alley had been close "until recently."
"We had a great relationship that I thought we had a great relationship," he said. "If it was something else or not I don't know. But I got a message that now that I am now associating with other people that she can't be associated with, I am no longer to be spoken with and sorry but it is what it is."
Chmerkovskiy also made it clear "I don't judge people by their religious beliefs." Alley was a member of the Church of Scientology.
"I just feel like, you know it's sad that we've gone through so much together, and I feel like I've helped her and this is where we're at now," he later added. "But I still think the world of her, and I wish her all the best."
Alley's children True and Lillie Parker announced her death on Dec. 5, sharing that their "incredible, fierce and loving mother" passed away following a battle with cancer that was "only recently discovered." The It Takes Two star was 71.
"She was surrounded by her closest family and fought with great strength, leaving us with a certainty of her never-ending joy of living and whatever adventures lie ahead," they wrote in a tweeted message. "As iconic as she was on screen, she was an even more amazing mother and grandmother."
Chmerkovskiy wasn't the only one to pay tribute. Several of Alley's former castmates also honored her.
"Kirstie was one of the most special relationships I've ever had," John Travolta, who co-starred in the Look Who's Talking movies with Alley, wrote on Instagram. "I love you Kirstie. I know we will see each other again."
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