Kardashian — who has an infant daughter, Dream, with Chyna — seemingly tried to get back at his former flame by uploading photos allegedly featuring her bare breasts, vagina and butt.
"This is from Chyna yesterday to me," Kardashian captioned one of the lurid shots. "I never been so disrespected in my life. I just bought her 250K of jewelry yesterday. This woman is so disrespectful and I don't care."
In a series of additional posts, Kardashian claimed Chyna hooked up with another man shortly after sending him one of the nude photos.
"This is the dude Chyna got caught cheating on me with for a minute now," Kardashian wrote, sharing photos of text messages he had received. "And look he texted me asking for help and said he needed money cuz he can't afford to pay Chyna's bill so that's why I pay her bills."
"More receipts are coming. Just yesterday Chyna sent me her p---y and everything and said she gonna come f--k me ... wait for it. Never once have I cheated on Chyna and I remained loyal to her even after all the cheating she been doing and the multiple men she been f--king including me."
In another post, he said the man threatened to "expose" Chyna if Kardashian didn't send him money.
Kardashian lamented that the man posed for a photo in the bed he used to share with Chyna. The reality star also rattled off a list of big-ticket items he bought for her.
"This the dude that posted a pic in the same bed Chyna and I made our baby in," Kardashian wrote. "The house that I pay for. That robe i prob paid for. Imma send u messages from this dude asking to link with me or he gonna expose Chyna if I don't help him get money cuz he can't handle the bills to take care of Chyna. Lol."
"I pay lambo. Ferrari. Down payment on the rolls. Downpayment on your moms car. I pay your mother since u won't even call your own mother back in months. I prob spent a million alone in the past 2 months. 90K necklaces. 70K watch. The Ferrari that u pretend u got yourself. Chyna I hope U find help."
Over the course of the lengthy online tirade, Kardashian accused Chyna of sleeping with other men in recent weeks as well, alleged she used drugs and alcohol while she was in the same house as their baby and posted what appeared to be her phone number to Instagram. A call to the number revealed it is not currently in service.
Kardashian also claimed to have paid for surgeries that Chyna underwent to get her pre-baby body back shortly after giving birth, and repeatedly shared a video of Chyna making out with another man.
"Hahahaha Chyna just sent me this video saying happy 4th of July what a crazy person," he wrote. "Come spend time with your daughter instead of f--king me and then this dude right after. U need help."
Chyna eventually retorted on Snapchat by accusing Kardashian of beating her and promising that the "light will come to light."
"Rob u did all this but u beat me up and try act it never happen !!!!! U put hand on me I swear on god !!!!!! On my kids but I'm supposed to be quiet because you're a Kardashian."
Many of Kardashian's explicit pictures were removed shortly after they were posted, presumably by Instagram, but he continued to re-share them. His account has not been taken down by the photo-sharing app more than two hours after his first post.
He continued to rip Chyna in his photo captions, writing in another, "u chose drugs and sex in our bed rather then spending it with your daughter for her first 4th July."
The social media exchange left many social media users stunned, including some who criticized the stars for not behaving like parents.
"Oh look @robkardashian having another breakdown on Instagram," tweeted a user named Annabel. "What great parents these two are, poor dream."
Kardashian and Chyna first began dating in January 2016 and were engaged three months later. They announced Chyna was expecting in May, and they welcomed their daughter in November.
But the duo experienced hardships in the relationship in the subsequent months, and a report surfaced in April that Chyna had returned her engagement ring to Kardashian.