1.You broke your word! – Non hai mantenuto la parola!
2.You didn’t follow through with it. – Non hai mantenuto la parola data.
3.You didn’t hold true to your promise. – Non hai mantenuto la tua promessa.
4.You didn’t deliver on your word. – Non hai mantenuto la parola.
5.You didn’t keep your promise. – Non hai mantenuto la tua promessa.
sources: Cambridge Dictionary; Native Speaker Teaches 20 English Slang Words, AccurateEnglish