The track is called Better Man but she won't be singing it herself - it's been penned for country band Little Big Town.
"But your jealousy, I can hear it now," go the lyrics, "you're talking down to me like I'll always be around".
"You push my love away like it's some kind of loaded gun" she also writes.
The band has confirmed in a Facebook Live Q&A that Taylor is behind the track.
"She sent us this song, and it was one that was really special to her," singer Karen Fairchild explained to fans.