Friends no more!

In Touch can exclusively reveal that Rihanna and her one-time pal Naomi Campbell are totally done now that the singer is dating Naomi’s ex Hassan Jameel.

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“If someone gets on the wrong side of Naomi, she doesn’t hold back, and right now she feels like Rihanna stabbed her in the back,” says an insider. “Naomi doesn’t forgive easily and has no interest in speaking with Rihanna ever again. It’s sad because Rihanna and Naomi used to be so close, but this romance is the nail in the coffin. There is no coming back from this.”

The source adds that the two have been “on the outs for several months,” but “Naomi is stunned that Rihanna would stoop this low.”

Sometimes it seems like the Barbadian beauty can’t catch a break from her highly-publicized love life. In the past, she’s dated Chris Brown and Drake — and has even been rumored to hook up with Leonardo DiCaprio. She was caught in a steamy make-out sesh with Hassan — the heir to Saudia Arabia’s largest Toyota distributor and soccer league owner — in Ibiza last week.

As for her former friend, the insider notes that RiRi “knew this was going to cause problems, but couldn’t care less about what Naomi thinks, says, or sees.”

This whole situation is ironic, however — considering she had a lot to say when her former pal Jennifer Lopez started dating Drake. At the time, a source told In Touch that she “branded her former pal a traitor.”

“Rihanna and Jennifer used to be good friends. She’s even confided in J.Lo about her rocky relationship with Drake over the years. Rihanna is very hurt,” the source explained back in January.

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It sounds like things could get ugly.

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