Gwen Stefani is opening up about the true story behind her duet with boyfriend Blake Shelton — and how scary the process was for her. As People reports, on tonight's episode of Chelsea Handler's new Netflix talk show, Chelsea, Stefani says that Shelton wrote the song "Go Ahead and Break My Heart" and sent it to her phone. While the singer says she was excited, she also had one big fear. "He's like, 'I wrote this song' and I was like, 'Whoa what if I don't like it, huge turnoff!'" Stefani explains. Luckily, Stefani says she listened to it and those fears went away. "I thought, Oh my god I love this," Stefani recalls. "He said, 'Write the rest of it.'" But that request came with a whole new set of worries. Stefani admits to Handler that she was feeling insecure about her writing after her divorce from husband Gavin Rossdale in August 2015. "There was such a drought of time when I was so insecure," she says, before adding, "I think when you have a really long year, you start to compete with your own self and get insecure about, 'I did that, but how did I do that?'" Shelton has also said that the duet was about facing down insecurities, telling People, "We both had trust issues. We were getting over it, but we wrote this song about it, and it's perfect." The duet appears on Shelton's new album, If I'm Honest, out May 20.