Do you think blackmailing is the most harmful suffering to do to a person, and the most undesirable, psychologically?

No. Scaring the person (if he hates spiders, put him in a room of spiders) is at least as effective.

Or threatening to kill loved ones.

Are you planning anything we should know about?

@elbanditoroso: What are you saying? Why should I blackmail anyone?

Being the victim of subterfuge is worse, in my book. Especially when the person responsible is unknown.
Being framed is a more common definition for subterfuge, in this instance.

No, of course not. For example,watching my child be deliberately hurt by someone would be worse.

@canidmajor Great point. Hurting someone I love is far worse than anything you could do to me.

Seems like a peculiar question. No, it would really depend on the specifics.

No.

I would certainly nominate physical torture for the number-one spot.