Maybe he did his bullshit because he thinks smoking is disgusting and wanted her to quit doing it ("I should quit, I know") if that is what caused the relationship to end. It sounds like its's about an addict who had gotten out of a relationship with a man who happened to be one of those types of people who thinks that smoking is disgusting and he kept telling her she had to quit ("I should quit, I know" again). If something else ended the relationship in case the man either was a smoker also or was a hypocrite who made her quit when he did it himself, then she's just taking his rejection out on her lungs.
Maybe he did his bullshit because he thinks smoking is disgusting and wanted her to quit doing it ("I should quit, I know") if that is what caused the relationship to end. It sounds like its's about an addict who had gotten out of a relationship with a man who happened to be one of those types of people who thinks that smoking is disgusting and he kept telling her she had to quit ("I should quit, I know" again). If something else ended the relationship in case the man either was a smoker also or was a hypocrite who made her quit when he did it himself, then she's just taking his rejection out on her lungs.