I don't think this is shade or even a necessarily offensive thing to say - She's just (jokingly) saying that she hates herself cause she knows she'll full into a full on stan if she keeps listening to the song.
If anything she's praising Selena for creating an addictive pop song.
You all continually do the most with these 'shade' comments
Also as others have said, she was 14 at the time
