The Selena/Justin/Kendall love triangle just got more complicated — because Kendall and Justin actually started hooking up WHILE he was still dating Selena, a new report claims. And, to make matters worse, she caught them in action!

Justin Bieber, 21, and Kendall Jenner’s, 19, romantic relationship behind Selena Gomez’s, 22, back actually began long before they became friends with benefits earlier this year. It was actually after the 2014 Coachella festival that things started heating up…and a devastated Selena shockingly found out about what was going on firsthand, according to a new report!

Poor Selena! She totally found out in the worst way possible that her boyfriend and best friend had committed the ultimate betrayal, Life & Style reports.

“After the Coachella festival last April, when Selena and Justin were still a couple, Selena showed up at his house and walked in on him and Kendall in bed together, fooling around,” the mag’s insider claims. “Selena was heartbroken and literally freaked out.”

Although the “I Want You To Know” singer eventually took Justin back for a few more months, the whole thing completely ruined her friendship with Kendall. “For months Selena sent her angry texts and insulted her,” the mag adds. “She was really mean to Kendall, but who could blame her? She thought she was her friend.”

But despite how furious Selena was that Kendall and Justin had gotten together, it didn’t stop them from rekindling the relationship this year. Although they never became an exclusive couple, the reality star and singer indulged in a secret relationship full of hot hookups for weeks. And to dig the knife in Selena’s back a little deeper, they attended Coachella together again this year! Ouch!