Selena Gomez allegedly caught on-again, off-again boyfriend Justin Bieber in action with his rumored flame Kendall Jenner while she was still dating him.

According to Life & Style, via HollywoodLife.com, Gomez "walked in on" Bieber fooling around with Jenner in bed at his house after the Coachella Valley Music and Arts Festival last April. At this point, she was still in a relationship with him.

The source said that the alleged incident broke Gomez's heart.

The friendship between the "I Want You to Know" singer and the "Keeping Up with the Kardashians" star was supposedly ruined ever since.

"For months, Selena sent her angry texts and insulted. She was really mean to Kendall," the publication reported. "She thought she was her friend."

A source recently told HollywoodLife.com Gomez actually knew all along that her then-boyfriend was hooking up with Jenner behind her back, because many people told her about it. One in particular, made her more aware of the supposed situation. Bieber's close friend, who Gomez completely trusts, reportedly told her about it.

Still, it is difficult to tell where these two stand.

At the Met Gala, which took place on May 4, Bieber was stunned by his ex-girlfriend's beauty.

According to HollywoodLife.com, he was videotaped while he shouted out of his car, "Yo, Selena looked gorgeous at the Mell Ball."

"He didn't say anything about Kendall looking gorgeous, did he?" another source told HollywoodLife.com. "That made her feel like she won the Met Ball."

The source added that Gomez "still loves the guy." However, the split from Bieber negatively affected her self-esteem.

"She knows comparing herself to anyone else is the worst thing to do and she tries so hard to avoid it but it's not easy when your ex-boyfriend is hooking up with supermodels," the source said.

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