Shane Powers credits the 'Sweetener' singer for being supportive of the rapper prior to his death last weekend.
In the latest episode of his podcast, The Shane Show, Powers opened up about Miller's battle with addiction. At one point, he even credited the late rapper's ex-girlfriend, Ariana Grande, for being "unbelievably involved and helpful" with Miller's sobriety journey.
"[Mac and Ariana] were very much in love and I have to say, she was incredible when he was first sobering up," Powers said. "She was a f**king G to him. There could not have been anybody more supportive of him being sober than Ariana. I saw that, I was around it, I took phone calls from her. 'How do I help? What do I do?' This little girl was unbelievably involved and helpful to him being healthy."
"Whether he's an addict or not, the way that Mac partied was not healthy," Powers continued. "[And] there was no one in his life more ready to go to the wall for him when it came to him being sober. [Ariana] was an unbelievably stabilizing force in his life and she was deeply helpful and effective in keeping Mac sober and helping him get sober. She was all about him being healthy. Period."
Prior to his death, Miller was arrested and later charged with two counts of driving under the influence in August following a May DUI arrest in Los Angeles, California. A spokesperson from the LA City Attorney's Office told ET on Monday that the case is now expected to be dropped.
"Typically when we have a defendant that has passed away while a criminal case is pending our office will take steps to have the matter removed from the court schedule and later file a motion to dismiss the case in the interest of justice," the spokesperson said. "The motion in the Miller case has not yet been filed, but I anticipate the office will take those steps within the next few days."
Grande and Miller called it quits in early May after nearly two years of dating, and the "Sweetener" singer has since moved on with Saturday Night Live star Pete Davidson. When the two became engaged in June after just a few weeks of dating, many slammed Grande, with some even blaming her for Miller's DUI and, eventually, his death.
The 25-year-old singer spoke out via Twitter following Miller's initial arrest, responding directly to one of the trolls who believed it was her fault the rapper -- who had always been vocal about his struggles with sobriety and depression -- ran into trouble with the law.
"How absurd you minimize female self-respect and self-worth by saying someone should stay in a toxic relationship because he wrote an album about them, which btw isn't the case (just Cinderella is ab me)," Grande tweeted at the time. "I am not a babysitter or a mother and no woman should feel that they need to be. I have cared for him and tried to support his sobriety & prayed for his balance for years (and always will of course) but shaming/blaming women for a man's inability to keep his s**t together is a very major problem."
"Let's please stop doing that," she continued. "Of course I didn't share how hard or scary it was while it was happening but it was. I will continue to pray from the bottom of my heart that he figures it all out and that any other woman in this position does as well."
Since Miller's death, Grande has yet to publicly break her silence but shared a captionless, black-and-white shot of her ex-boyfriend to Instagram.
A source also told ET that the Boca Raton, Florida, native is "devastated" by her ex's death.
"Although the two ended their relationship, Ariana always shared a deep connection with Mac and wanted nothing but the best for him," the source added. "Ariana is very upset."
Hear more on Miller in the video below.