At another interview with Power 105.1 Melly talks more about having multiple personalities, which he claims are 6, and gives a break down on half of them.
In an interview with Bootleg Kev and DJ Hed Melly talks about his song with Kanye, Mixed Personalities. During the interview he reveals that he is Bipolar and claims to have multiple personalities.
Melly turned himself in because he realized what Melvin did and the guilt was too hard on him. In the caption he's somewhat vague since he knows he didn't do it himself because he thinks of Melvin as a whole other person.
My theory is that Sakchaser and Juvy may have done something to Melly and Melvin didn't like it. Melvin may have convinced himself that they were out to get him and his only way to get rid of them was to take over Melly and do it himself.
The titles to Mellys last 2 projects are actually messages from Melvin to Melly and the rest of the world.
"I am you"
"(U Shine, I Shine,) We All Shine"