Demi Lovato is honoring their late friend. The 29-year-old singer took to Instagram on Saturday to announce the release of a new song, "Unforgettable (Tommy's Song)," in honor of their late pal, Thomas Trussell III, who died in 2019 after a battle with addiction.«Two years ago I lost someone who meant so much to me,» Lovato wrote alongside a snippet of the song.