make a clear breast of it

make a clear breast of it (to confess fully) — облегчить душу, снять с души камень; честно во всем признаться; чистосердечно признаться

Example 1: After Jack's wife found the girl's underwear in their bedroom, Jack decided to make a clean breast of it and tell her about the affair.

Example 2: A judge might be more lenient towards criminals who make a clean breast of their crime.

see also
[come clean]
[get sth off one's chest ]
[out of one's system]