Welcome to Heartbreak City, population: Blac Chyna.

Kim Kardashian says that her one-time friend Chyna, 28, was really hurt when Kardashian’s youngest half-sister Kylie Jenner began dating the Lashed Bar entrepreneur’s ex-fiancé, Tyga, in a preview for the Sunday, May 22, episode of Keeping Up With the Kardashians.

“I understand that Kylie dating Tyga completely broke Chyna’s heart. I feel for her in that situation,” the reality TV superstar, 35, tells the camera in the clip above. “Was it uncomfortable for me when Kylie and Tyga started to date? Absolutely, because Chyna was my friend.”

“But I had no choice but to take my sister’s side,” Kardashian says. “That’s my sister.”

In the same scene, the Selfish author sits down with her siblings Kourtney and Khloé Kardashian to tell them that their brother, Rob, tried to force Kim to reconnect with the former stripper over the phone.

“So I called Rob and he said that Chyna wants to talk to me and, you know, I just told him that I’ll talk to her when I’m ready,” Kanye West’s wife recounts to Kourt and KoKo. “And so he put me on speaker and then he was like, ‘Oh Kim, Chyna’s in the room. I just wanted to tell you so you didn’t think I was alone.’ And so she goes, ‘Hi,’ in the background and so I didn’t say anything.’”

Khloé gasps and asks: “You didn’t say hi?”

“No, I did not know what to say. I froze. No, he goes, ‘Hold on, I’m gonna brush my teeth, you talk to her,’” Kim continues. “And so I go, ‘OK, gotta go. Bye.’ And I hung up. I just wasn’t ready, you know, and I’m not gonna be forced to be on the phone with her. I’ll talk to her when I am ready.”

“Do I think that everyone needs to sit down and talk? Absolutely,” the mom of North, 2, and Saint, 5 months, adds to the camera.

Tyga, 26, and the Kylie Cosmetics founder were rumored to be an item as early as October 2014, when Jenner was still a minor at age 17. They went public with their relationship in late 2015, after the teen E! personality’s 18th birthday.

As Us Weekly previously reported on May 12, the duo recently called it quits. A source told Us they broke up earlier this month. A second insider added that “Kylie and Tyga are not speaking right now.”

It’s not necessarily permanent, though. “They fight and get back together all in the same day constantly, so last week she didn't want to say it was a breakup as that's how it always is,” another source explained to Us. “We've been down this road before.”

Jenner’s romance with Tyga seemed to inspire the unlikely — and vengeful — relationship between Chyna and Rob, 29. While Tyga and Jenner have fizzled, Chyna (the mother of the “Rack City” rapper’s son, King Cairo, 3) and Rob are still going strong.

Back in January, the Arthur George sock designer and the video model went public with their romance. In April, they announced their engagement, and in May, Chyna revealed she is pregnant and expecting her first child with Rob.

Tyga congratulated Chyna on her pregnancy with an Instagram comment, but Kylie has yet to publicly acknowledge the fact that her brother is having a baby with her now-ex-beau’s baby mama. (Yes, we still get confused by this, too!)

Watch the clip above. Keeping Up With the Kardashians airs on E! Sundays at 9 p.m. ET.

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