The new season of E!’s Keeping Up With The Kardashians is shedding light on the family’s real relationship with Rob Kardashian’s fiancée, Blac Chyna, as Kim Kardashian finally reveals why she ended her previous friendship with Chyna.

Fans might remember that Chyna and Kim were actually pretty good friends at one point. But when Kim and Rob’s youngest sister Kylie Jenner started dating Chyna’s ex Tyga (Tyga and Chyna also have a son together), Kim proved once again that the Kardashian motto is family first and stopped being friends with Chyna.

Now that Rob and Chyna are engaged and expecting a child together, Kim has confessed why she felt like she needed to cut ties with Chyna.

In a teaser for the upcoming episode of Keeping Up With The Kardashians, Kim reveals to Kourtney and Khloe Kardashian that Chyna told Rob she wanted to speak with her. While Kim said she needed time, Rob instantly put her on the spot and said, “Oh Chyna’s in the room,” forcing the two ex-friends to talk.

Even though Chyna spoke to Kim, Kim panicked and said, “Okay I gotta go” and hung up the phone.

Still, she told cameras, “I understand that Tyga dating Kylie broke Chyna’s heart. I feel for her in that situation. 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… Like, that’s my sister. Do I think everyone needs to sit and talk and work everything out? Absolutely.”

See what happens when the full episode airs Sunday at 9/8c on E!

Tags: Keeping Up With The Kardashians Reality TV E!