Ray J was the one who had been on the infamous sex tape with Kim Kardashian. In an episode of 'The Kardashians', West revealed that he had got hold of the tape from Ray J. But the latter denied the claims and stamped it as a fake publicity stunt.
Their friendship went downhill as the rapper spoke ill of Jay Z and his family during his Saint Pablo Tour in 2016. Even before that there were troubles as West forced the Carters to hang out with Kim Kardashian. Jay Z did not even Kanye's wedding.