[artist id="502642"]Eminem[/artist] has always maintained that the [article id="1528386"]death of his best friend and D12 member Proof[/article] was one of the most devastating moments of his life, and four years after his passing, Eminem is still upholding the late MC's legacy in his music.

On Thursday (December 30), the Em track "Difficult" surfaced on the Web, in which the Detroit lyricist devotes several bars to his relationship with his fallen homey -- who was gunned down in a Motor City nightclub in 2006 -- and how the memory of his trusted friend still lingers.

"Doody, most of my life it's just been me and you there/ I continuously stare at pictures of you/ I never got to say 'I love you' as much as I wanted to, but I do/ Yeah, I say it now when you can't hear me/ What the f--- good does that do me now?/ But somehow I know you're near me," Em rhymes in the first verse. On "Difficult," a solemn, hook-free record powered by somber chords and a glacially slow beat, Eminem speaks on the enduring impact the loss of Proof has had on his life and the lives of their mutual friends.

"Everyone else is just trying to pick up the pieces/ Man, how could you touch so many f---ing lives and just leave us?" he spits. "They say grievance has its way of affecting everyone different/ If it's true, how the f--- I'm supposed to get over you?"

Em also opens up about the duo's bond as childhood buddies who remained close friends for much of their lives until Proof, born DeShaun Holton, was killed at age 32.

"Doody, that's what we called each other/ I don't know where it came from, but it just stuck with us, we was always brothers/ Never thought about each other's skin colors," Em rhymes. The Recovery star also speaks candidly about cherishing an article of clothing Proof wore during a special moment in Em's life.

"And this may sound a little strange, but I'mma tell it/ I found a jacket that you left at my wedding, I picked it up to smell it/ I wrapped it up in plastic until I put it in glass and hang it up in the hallway so I can always look at it," he raps.

Em also hints at the controversy surrounding Proof's violent death. The D12 rapper allegedly shot a fellow clubgoer at the Detroit haunt CCC and was shot and killed by a bouncer who was related to Proof's shooting victim. A local prosecutor later ruled that the [article id="1533221"]bouncer was acting in his cousin's defense[/article] and did not face murder charges. In "Difficult," Em paints a portrait of Proof as a peaceful person who wouldn't have resorted to violence unnecessarily.

"You were the peacemaker, Doody/ I know sometimes you were moody, but you hated confrontation and truly hated the feuding/ But you was down for yours whenever it came to scrappin'/ If it had to happen, it had to happen," he spits.

The leaked track isn't the first time Shady has turned to music to eulogize his late friend. Em said earlier this year that [article id="1643029"]"You're Never Over," from his chart-topping seventh album, Recovery,[/article] "finally did Proof some kind of justice by being able to put that together and dump my heart on the record."

What do you think of Eminem's "Difficult" track? Let us know in the comments.