between you and me
US /bɪˈtwin ju ænd mi/
UK /bɪˈtwin ju ænd mi/

1.
ここだけの話, 内緒で
said when you are telling someone something confidentially
:
•
Just between you and me, I think he's going to resign.
ここだけの話だけど、彼は辞任すると思うよ。
•
What I'm about to tell you is strictly between you and me.
これから話すことは、ここだけの話だよ。