Disintegrarmi means 'to disintegrate me' or 'to break me into pieces'. It's a dramatic and vivid verb that evokes a strong image of complete destruction.
In the song, the artist uses this word to express the overwhelming power of his love interest. He sings, "Se fossi minuscolo, salterei sulle tue mani / E ti basterebbe stringerle a disintegrarmi" (If I were tiny, I would jump into your hands / And it would be enough for you to squeeze them to disintegrate me). This hyperbolic imagery emphasizes the profound impact she has on him, suggesting that her mere touch could utterly undo him, making it a memorable and emotionally charged word.
Kid Yugi builds this whole song out of things that never happened. The first verse is a list of negations, and they get more specific as they go: "La figlia che non avremo spero che abbia i tuoi occhi" (The daughter we won't have, I hope she has your eyes), "La casa che non compreremo è piena di ricordi" (The house we won't buy is full of memories). It is a strange trick, grieving a life you never started. He says it outright in the second verse: "Ho preferito immaginarti piuttosto che viverti" (I preferred imagining you rather than living you). The woman in the title stays an idea rather than a person, and the chorus keeps moving her out of reach: "Tu sei un sogno di libertà" (You're a dream of freedom), then "Ma te ne sei tornata già a Parigi" (But you've already gone back to Paris).
The best image is the one where drawing her turns violent. He keeps sketching her on thin paper, "Che a furia di ricalcarti saranno a brandelli" (That from tracing you over and over will be in shreds), "Finché non distingueremo matite e coltelli" (Until we can't tell pencils from knives). That is the song admitting what it is doing to itself. There is a real memory in there too, or something shaped like one: "Sei sparita sulla Quinta Strada nel fumo dei tombini" (You vanished on Fifth Avenue in the smoke from the manholes), "Mentre ti urlavo in italiano, 'Che cosa combini?'" (While I shouted at you in Italian, 'What are you up to?'), which is funny and sad at the same time, shouting in a language she may not even speak. Then he asks whether any of this helps: "Chissà se basterà descriverti ad esorcizzarti" (Who knows if describing you will be enough to exorcise you). The song does not answer.