Help Deciphering Sentence in Old italian Script

[kahb3]

We have a musical score of Giovanni Puccini’s La Boheme dated about 1898 with a sentence handwritten across the top of the title page in old Italian script and perhaps signed “GP”.

Can you help us decipher what the words are and what the sentence says?

It might help us confirm the initials are the composers.

Thank you

[liviomoreno]

Be as happy as it is great the unhappiness that you procured to me
Milano, December 22 1902

(you made me unhappy but I wish the same amount of happiness)