If you are looking for a digital version of the English translation (translated by Michael Caesar and Franco D'Intino), you can find it through the following resources:
He wrote: "He who has the courage to be unhappy is the only one who can be truly happy." Zibaldone English Pdf
The English translation, first published in full in 2013, was a landmark event in world literature. It revealed Leopardi not just as Italy's greatest lyric poet, but as a precursor to modern thinkers like Nietzsche, Freud, and Beckett. If you are looking for a digital version