more than you know

more than you know

To a much greater degree than you suspect, understand, or are aware of right now. A: "Are you sad to be leaving Washington, D.C., behind?" B: "Yes, more than you know." I know you think I'm cruel for the way I handled things, and that saddens me more than you know. To everyone who has donated or shared words of compassion with us, I just want to say that your support during this tragedy means so much more to us than you know.
See also: know, more
Farlex Dictionary of Idioms.

more than you('ll ever) know

a great deal, more than you suspect. Bob: Why did you do it? Bill: I regret doing it. I regret it more than you know. John: Oh, Mary, I love you. Mary: Oh, John, I love you more than you'll ever know.
See also: know, more
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • more than you can (ever) know
  • more than you will ever know
  • the White House
  • go-go
  • the Hill
  • (Is) everything OK?
  • catch (one's) drift
  • (Is) life getting you down?
  • (Are) things getting you down?
  • come out to be