speak confidentially

I never knew a woman to speak confidentially of matrimony otherwise than as a matter of pounds, shillings, and pence.

I certainly should not speak confidentially to a man that I meet for the first time, and so disclose any of my own purposes.

She was able to speak confidentially to Mr. Rayburn, while Lucy was in the balcony hugging her doll, and looking at the sea.

We sat down, and began to speak confidentially with one another.

I come now to speak confidentially to you on a private subject.