Nick Carter broke down in tears during his Sunday performance with the Backstreet Boys at London's O2 Arena.

Nick Carter said he is completely shocked by the death of his brother, Aaron, and has expressed his love for his younger sibling despite their complicated and sometimes difficult relationship.

In a lengthy dedication posted on Instagram, Nick said his heart is "broken". Nick's full statement reads:

"My heart is broken. Even though my brother and I have had a complicated relationship, my love for him has never wavered. I have always held out hope that one day he would want to walk a healthy path and finally find the help he so desperately needed. Sometimes we want to blame someone or something for a loss, but the truth is that addiction and mental illness is the real culprit here. I will miss my brother more than anyone. Know that I love you Chizz. Now you can finally have the peace you could never find here on earth… I love you little brother."

As you may know, Nick and Aaron almost never saw eye to eye during the course of their relationship ... And Nick publicly acknowledged this fact, revealing that his brother struggled with drug addiction and mental illness.

Aaron was found dead in his LA home on Saturday morning after police received a call about a man drowning in a bathtub.

Authorities have not confirmed an official cause of death, but police are said to be doing a deep dive into his past drug use.

In addition to Nick, Aaron's twin sister Angel Carter also paid tribute to her brother in an Instagram post, vowing to cherish their memories.