Funny you should say that!?

FYI:
I have trouble to understand the following sentence (my, Simon, poor writing 1 year ago)
I have trouble UNDERSTANDING the following sentence:
We sometimes use 'should' to express surprise or regret about something that happened:
"I’m amazed that he should have done something so stupid." : = He did 'something stupid' and I am surprised that he did.
It is strange that a clever person like you should have believed him.” = 'you' believed 'him', and I am surprised, because 'you' are a clever person and YOU SHOULD HAVE REALISED he was lying/being deceitful.
Bazza · 1 year ago

The form" should not have" are much less frequently used in USA even
to talk about the past=rare in American English.!!!!!!!!!!!!!
You shouldn't have lied to me that way (as =if) you had not been my munshi(="文書").
既然是"文書"宗教老師,就不應該欺騙我.罪該萬死殺無赦殺無赦!!!!!!!!!!!!

"It is unconscionable that as my munshi you should have lied to me in any way."==你既然是宗教老師,就不應該欺騙我. Yip