Scarlett Johansson’s high-school ex-boyfriend, Jack Antonoff, is still singing about how he’s not over her. His band, Steel Train, begins a Sunday-night residency at Pianos on the Lower East Side on March 26, where his broken heart will be on display. Antonoff dated the starlet while they both attended the Professional Children’s high school (class of ’02). The song “Better Love” is about their relationship, and Antonoff’s pining for the girl who’s now Josh Hartnett’s sweetie: “Fame swept her off her feet / She sees nothing she did before . . . Hey, Scarlett, you’re not the same.” Johansson’s moniker is also mined for metaphor: “Scars are in her name / And she scars me in blame.” Other lyrics seem to refer to Johansson’s role in 2003’s Girl With a Pearl Earring, to quasi-devastating effect (“I watch the camera shoot this girl / Seems to me a hollow pearl”), and the track concludes on a bittersweet note: “Some years have passed / I say I don’t, but I miss her bad.” Antonoff says they dated “all through high school,” and that they’re still close; Johansson’s publicist would only admit to a senior-year relationship.