Mariah Carey has apologized for her performance at the Michael Jackson Memorial Service in Los Angeles on Tuesday.

Nearly 20,000 fans, celebrities, and public figures attended the memorial service at The Staples Centre in Los Angles, which also included performances by Jermaine Jackson, Stevie Wonder, Jennifer Hudson, John Mayer, and Usher.

The multiplatinum-selling singer faltered during her rendition of The Jackson 5′s “I’ll Be There” with Trey Lorenz. In a series of poignant messages posted to her Twitter account last night, Mariah blames the shaky performance on becoming overcome with emotion after seeing the icon’s coffin.

“Trying to sing today was basically impossible for me. I could barely keep myself from crying,” Mariah later Tweeted.

“I’m sorry that I wasn’t able to pull it together and really do it right, but I was literally choked up when I saw him there in front of me….One thing I know is, we will never really have to say goodbye to MJ. His legacy lives on through his music and the millions of people he inspired with his timeless music. He will be forever in our hearts.”