Justin Bieber needs to learn a lesson from the Backstreet Boys and quit playing games with Kourtney Kardashian’s heart! As one of his many love interests, Kourtney attended Justin’s concert on March 23, but it was his ex, Selena Gomez, who got all of his attention. And that irritated Kim.

Kim Kardashian went into full-on protection mode, when Justin Bieber spent most of his Wednesday night with Selena Gomez, and didn’t pay very much attention to Kourtney, who also attended his March 23 concert in Los Angeles. Kim wasn’t too happy when Justin made Selena his priority, despite recently “hooking up” with Kourtney, so at an after-party, she gave the 22-year-old singer a piece of her mind!

“Kim pulled Justin aside last night and berated him. In a very calm voice and her eyes looking through his soul, Kim told Justin to stop playing with Kourtney’s emotions. She told him that Kourtney’s been through enough with Scott and the last thing she needs is to be tangled up in yet another love triangle. Kim asked Justin if he knew what the word vulnerable means, and he said no. She told him his homework assignment was to look it up, understand the meaning, and to think of Kourt when he reads the definition because that’s where she’s at in her life right now. Kim really didn’t want to ruin Justin’s night by talking his ear off and preaching to him, but she doesn’t want anyone messing with her family,” a source tells

Good for Kim! We love how she’s sticking up for Kourtney. While we’re huge fans of this recent Jelena reunion, we also feel bad for Kourtney, who doesn’t need to be disrespected. She’s very vulnerable right now. Luckily, Kourtney and Selena did not cross paths last night. But if Justin keeps this up, it’s only a matter of time before they do.

What do YOU think? Is Justin playing with Kourtney’s emotions? Tell us below!

by Chris Rogers for Hollywoodlife