The song you're thinking of is Life Is Beautiful by Sixx:A.M.
The lyrics "Will you swear on your life, that no one will cry at my funeral" actually originate from a quote by Robbin Crosby, who died from a heroin overdose after being introduced to the drug by his friend and room-mate, Nikki Sixx (founder of Sixx:A.M.).
About Life Is Beautiful
Life Is Beautiful was the first single to be released from Sixx:A.M.'s debut album, The Heroin Diaries Soundtrack. The song was recorded and released in 2007, to great commercial success.
Sixx:A.M. Are a hard rock band from Los Angeles. They were formed in 2007 by Nikki Sixx, the founder and bassist of Mötley Crüe.
Their first album, The Heroin Diaries Soundtrack, accompanies Sixx's autobiography, which is titled The Heroin Diaries: A Year in the Life of a Shattered Rock Star. Both the album and the book detail Nikki Sixx's heroin addiction (whilst with Mötley Crüe) and his subsequent recovery.
The band's second album, This Is Gonna Hurt, was released in 2011.