"We all have someone in our lives that no matter what they do and how bad it hurts, you still love them," Nick, 42, wrote on Instagram about the "I Want Candy" singer. "So I worked it out the best way I know how."
In the teaser clip of the video, Nick sings as old footage of him and Aaron playing as kids is seen on the screen. It also cuts to a time-lapse video of a rose blooming.
"Feel like we've been through some wars together," Nick sings in the ballad, which he co-wrote. "Nobody else could understand / Way too many nightmares to remember / But that was real life back then / Always hoped your tomorrow / Would be better than the days before / I hoped you'd find your road to follow / To a place you were happy in this world."
The chorus goes: "Cause it hurts to love you / But I love you still / Miss you with all my heart / You know I always will / I always prayed for peace my soul could feel / Cause it hurts to love you / But I love you still."
He also sings about it being "Hard to let go of the anger / I know for me it took some time / Sometimes the darkness lasts forever / Feels like the light won't ever shine."
The brothers famously had a tumultuous relationship. Aaron rose to stardom on the heels of Nick, opening for Nick's Backstreet Boys on tour at age 9, and then going on to launch his own musical career. The brothers appeared together in the House of Carters reality show. Their notorious fights on the show only got bigger years later on social media. Nick, as well as Aaron's twin sister Angel, received restraining orders against Aaron in 2019.
Aaron publicly struggled with addiction to Xanax, Oxycodone and huffing. He faced multiple arrests and did several stints in rehab. On The Doctors in 2017, he revealed had been diagnosed with multiple personality disorder, schizophrenia, bipolar disorder and acute anxiety. He also struggled with eating disorders and body dysmorphia, weighing just 115 pounds that year.
Aaron was found dead on Nov. 5 — and no cause of death has been released pending toxicology results. A spokesperson for the LAPD said at the time it was a "suspicious death." Police sources told People magazine they believe he lost consciousness and drowned in his bathtub.
Nick posted an online tribute to him following the news, saying his "heart is broken" and even though they had "a complicated relationship" his "love for him has never ever faded."
Nick and Angel will co-host a benefit concert, Songs For Tomorrow, on Jan. 18 in West Hollywood, Calif., in their sibling's honor. Lance Bass, who said Aaron was like a little brother to him, will co-host with performances expected by members of the Backstreet Boys, NSync, O-Town and LFO as well as Ryan Cabrera. Proceeds go to On Our Sleeves: The Movement for Children's Mental Health.