Miller died on Sept. 7 of an apparent overdose.
The 25-year-old singer spoke out on Miller's death on Friday, a week after he was found dead on Friday inside his San Fernando Valley home, ET confirmed. According to TMZ, he died of an apparent overdose.
Grande, who disabled comments on her Instagram last Friday -- after fans blamed her for Miller's death -- remembered Miller as her "dearest friend."
"I adored you from the day i met you when i was nineteen and i always will," she wrote. "I can’t believe you aren’t here anymore. i really can’t wrap my head around it. we talked about this. so many times. i’m so mad, i’m so sad i don’t know what to do."
"You were my dearest friend. for so long. above anything else. i’m so sorry i couldn’t fix or take your pain away. i really wanted to," Grande continued. "The kindest, sweetest soul with demons he never deserved. i hope you’re okay now. rest."
The former Nickelodeon star posted a sweet black-and-white photo of her ex-boyfriend to her Instagram on Saturday.
Miller and Grande split after nearly two years of dating in early May. The singer addressed their breakup on Instagram, calling Miller "one of my best friends in the whole world." "I respect and adore him endlessly and am grateful to have him in my life in any form, at all times regardless of how our relationship changes or what the universe holds for each of us," she wrote.
Soon after, the rapper was arrested and later charged with two counts of driving under the influence in August following a May DUI arrest in Los Angeles, California. At the time, Grande, who moved on romantically with Pete Davidson, responded to a Twitter user who accused of her of being the reason behind the incident.
"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 sh** together is a very major problem," she said, calling her relationship with Miller "toxic."
"Let's please stop doing that," she added. "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."
A source told ET following Miller's death that Grande was "devastated."
“Although the two ended their relationship, Ariana always shared a deep connection with Mac and wanted nothing but the best for him," the source said. "Ariana is very upset."
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