Scheana is dropping a new song Friday called "Apples" ... in which some of the lyrics go like this ... "I was with you on your worst day / You stabbed me in the worst way / How you gonna lie to my face?"

Scheana wasn't done ... "And you said that we would always be friends / Party on the weekend / But then you’re gone without a trace; I thought you were grateful / I found out you’re fake, though / I hope there’s a place for friends like you."

Interesting ... saying "you're gone without a trace" suggests Scheana is completely done with her friendship with Rachel or she's pissed Rachel decided not to return to 'VPR' ... safe to assume the latter.

And get this ... Shay labels Rachel a "narcissistic psychopath" whom she "cut out like lipo."

Scheana was pissed at the time over Rachel having an affair with Tom Sandoval ... ultimately resulting in Rachel (then Raquel) getting a restraining order against her after claiming Scheana physically attacked her.

Scheana denied the whole thing, with her lawyer calling Rachel a "known liar and a cheat." As you know, Scheana won in the end -- with the whole thing eventually getting dismissed.