Blac Chyna is going to have to find another babysitter for son King Cairo.

Following her split from Rob Kardashian, Chyna, 28, is reportedly furious with his sister Kylie Jenner, 19, after she took his side in the pending custody battle over their daughter Dream.

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As payback, Chyna is determined to keep her four-year-old son away from Kylie, despite her relationship with his dad, Tyga.

Kylie's loyalty to Rob, 29, came as a surprise to the Lashed model, who recently reconciled with the KUWTK star after years of animosity.

kylie jenner king splash

Kylie with Tyga and King at Disneyland.

“Chyna’s surprised Kylie doesn’t have her back in this situation,” a source told Hollywood Life. “They’ve become so close. They’ve put everything behind them and Chyna basically trusted her with King."

The source continued, "Chyna’s got a bad taste in her mouth. She doesn’t think it’s smart to have someone she can’t trust and doesn’t have her back be present in her son’s life. King and Dream are her babies and the Kardashians won’t take them from her.”

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Meanwhile, Rob is looking better than ever and gushing about his four-month-old daughter on social media.

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A post shared by Blac Chyna (@blacchyna) on

"I took my baby girl for a nice hike today," he captioned a pic. "I LOVE THIS WOMAN 🙂 I will never tell her no lol and look at them eyes."

However, he is struggling with not living with Dream full-time since his split from her mom.

"Saying bye to my beautiful baby girl … she is smiling at me," he wrote. "U see how she looking at her daddy. I literally can't get enough of this girl … I never felt a love or happiness like this ever in my life and she makes me so happy … about to miss her so much."

Their breakup also means there will not be a second season of their reality show, Rob & Chyna.

"They are doing the best they can to stay civil and to co-parent the best they can," a source told Entertainment Tonight. "They have worked out an informal custody arrangement. They found out what works for them and they’re doing a good job at it."

For a look back at Chyna with her former BFF Kim Kardashian, click through the gallery below!