From Wiktionary, the free dictionary
Literally, “put one's heart in peace”.
méttersi il cuore in pace (first-person singular present mi métto il cuore in pace, first-person singular past historic mi mìsi il cuore in pace, past participle mésso il cuore in pace)
- (idiomatic) to resign or give up; to stop bothering with an assignment, burden, etc.
