Hetstaine is the James Hetfield/Dave Mustaine relationship from way back until '83 when Mustaine got kicked out of
Metallica. I can 100% Verify that Hetstaine is real. For example, the bathtub picture of them has been proven to be real, and there is interviews where James mentions the 'virgin territory' they covered together and the 'many things they did together that can never be undone'. Also, James never wanted
Dave to leave the band, Lars Ulrich gave James an ultimatum. It was either Mustaine leaves and James stays, or they both
go. Dave went and formed Megadeth, and then was all lovey with
Junior, which is the reason why James hated him so much (he was
jealous duh). When Cryptic Writings by Megadeth came out in 1997, there was a song called 'Trust' on it, which tells about a doomed relationship. (James/Dave were rumoured to have given the relationship another
shot around that time). Dave has also mentioned that he loves James in many different ways, through Twitter, Interviews, Instagram, etc.