"I told Brandon, man, you need to grow up and figure out that you need to marry this girl," Shelton told Hollyscoop that month, according to Us.
"I am going on the record saying, I will do the music at the wedding or whatever you want to do, I'll be that guy. I will play for four hours if I have to, cause you need to get your head out of your ass and ask that girl to marry you."
"I'M ENGAGED!!!!! I wanted y'all to know!! Happiest night of my life last night! I am so lucky and am with the greatest man ever," Clarkson tweeted.
Blackstock is the son of Narvel Blackstock, Clarkson's manager, and stepson of country singer Reba McEntire, who became friends with Clarkson after the women performed a duet on American Idol in 2002.
Clarkson signed with Narvel Blackstock's Starstruck Entertainment management company in 2007 following a feud with recording industry titan Clive Davis over the musical content of "My December," her third album.
Blackstock proposed to Clarkson with an engagement ring he designed with jewelry designer Johnathon Arndt.
"Everyone has been asking about my engagement ring... It's a yellow canary diamond with diamonds around it and Brandon designed it with Johnathon Arndt! They did an amazing job! I can't wait to make Brandon's ring with Johnathon as well!" Clarkson wrote in a follow-up tweet.
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