Chris Brown Says Migos' Quavo Betrayed Him by Dating Karrueche

Chris Brown is angry, feeling like he was stabbed in the back by Quavo from Migos ... a man he thought was a good friend until he started dating Karrueche Tran.

Our CB sources say ... Chris had both a business and personal relationship with Quavo ... inviting him to his home, collaborating on songs before Migos hit big, and supporting the group by attending multiple promotional parties.

Chris is livid that he actually helped promote Migos' recent hit album, "Culture," at the same time Quavo was secretly seeing his ex-girlfriend.

Chris believes it's no coincidence Karrueche got a restraining order against him at the very time she started getting tight with the Migos rapper. He believes this was orchestrated by both Karrueche and Quavo to clear the decks so they could date, without caring they would make him look like a chump.

Before Chris found out the 2 were dating, he did an interview with Billboard and called Migos "my real friends and brothers" and said, "I will never hate on you ni**as."

Well, now he does.