In John Carter Cash's book, he says June sometimes would reminisce about Elvis and wonder what it would have been like if she'd wound up with him. But that may have been her way of tweaking Johnny Cash, who apparently never found it very very easy to be true, to June or to his first wife. June said she told Johnny when he got rid of Elvis' letters that he shouldn't have done that - they were worth a lot of money (she was joking).
Never heard about June C. and Elvis, Johnny was jealous of Elvis? THat's kinda romantic that he burned her old love letters. Why did she keep them? boy that would've made a great c&w song!