“To all the souls messaging me about Kai – we are no longer together,” she wrote, adding that she was “not afforded any real explanation” for the breakup.
“While I appreciate your concern, as much of our relationship was on social media, I don’t know what to say except that I wish to put this behind me, and I am lucky to have people who love me to support me through this time x.”
She concluded the post by thanking her fans for their “ongoing love.”
The Untouched hit-maker has since unfollowed her former flame and deleted all the loved-up snaps that previously flooded her account.
It’s been just shy of a year since the pair first shared they were engaged, with Kai, 23, popping the question at an upmarket resort in Joshua Tree National Park, California.
Taking to Instagram, the beloved songstress shared a photo from the adorable proposal, showing off her sparkling ring.
"Happy 1 year & THE REST OF MY LIFE with you," she captioned. "I’ve been happy crying for 2 hours. I’ve never felt so full."
In August, Kai - who identifies as a trans male - penned an emotional tribute to Jess on social media, mentioning that times had been “tough” without physical contact.
“It’s been almost 6 months, 3 travel applications, hundreds of FaceTimes, and thousands of texts since. Though the times have been tough and trying, there is no one I appreciate, love and admire more in these times than you,” he wrote.
Before Kai, Jessica was in an on-again-off-again relationship with Australian actress and DJ, Ruby Rose, for more than a decade.
Speaking to KIIS FM's The Kyle and Jackie O Show, she previously shared that their romance was "complex".
"I'm still trying to come to terms with the reality of it every day so it's really hard to explain to anybody," the singer said.
"There was just so much that happened, so much that I can't even get into it. At the end of the day I think the most important thing to remember is that we’re all human beings, people have their struggles, people have their inner demons people have their own stuff going on.
"For me, it was time to leave that situation and be as happy and healthy as I deserve to be," she finished.