Dic: come clean (with someone) (about something)

• It would be better if you come clean about it and let her know what kind of man she is seeing.
• I want you to come clean with me about your financial status.
• Sam will come clean with me. I know he will.
• I felt it was time to come clean and tell her what the doctor had told me. (often + about )
• It's time for the Chancellor to come clean about the proposed tax rises.
• I should probably come clean now and admit that I don't really know how to cook at all.

1. If you come clean about something that you have been keeping secret, you admit it or tell people about it.[ INFORMAL ]
2. Fig. to be honest with somebody about something.
3. to tell the truth, often about something bad that you have been trying to keep a secret

... Cobuild, McGrow-Hill Idioms, Cambridge Idioms,

http://idioms.thefreedictionary.com/come+clean