(D, 2) Complex matters.

Introducing a secret.
Just between you and me...
Can you keep a secret?
Don't repeat this, but...
Don't let this get around, but...
Could you keep a secret?
Confidentially...

Instructions about keeping a secret.
Better keep quit about it.
Don't breathe a word of it.
Don't let it out of this room.
Don't let this go any further.
Don't tell a soul.
This is not for public knowledge.
This is not public knowledge.
This is not for publication.

Promising to keep a secret.
I won't tell a soul.
My lips are sealed.
It won't leave this room.
Wild horses couldn't drag it out of me.
I'll take it to my grave.

Forgetfulness.
Where was I?
What was I saying?
What were we talking about?
I don't remember.
I have a mind like a sieve.
I'm a little absentminded.
Are we supposed to be at some place right now?

 When you are in trouble.
I'm in deep.
I'm in over my head.
I'm in a way over my head.
My reputation is at stake.

When someone is in trouble.
You've really screwed up. (info)
You are up a creek. (info)
You are up the creek. (info)

When you are out of money.
I'm broke.
I'm flat broke.
I'm bankrupt.

Expressing stress or anxiety.
I'm going nuts.
I'm going crazy.
I'm loosing my mind.
I'm going to explode.
I'm coming apart at the seams.
I'm falling apart at the seams.

When you are overworked and doing too much.
I scarcely have time to breathe.
I've no time to call my own.

When someone is anxious and under stress.
Calm down.
Don't be such a worrywart.
Don't loose your sleep over it.