What meaning does "should have" express in this context?

Question

Then there's another thing. I had hoped you might have peddled that opium through the islands, which is safer and more profitable. But with this three-month limit, you must make tracks for Honolulu straight, and communicate by steamer. I'll try to put up something for you there; I'll have a man spoken to who's posted on that line of biz. Keep a bright lookout for him as soon's you make the islands; for it's on the cards he might pick you up at sea in a whaleboat or a steam-launch, and bring the dollars right on board.” It shows how much I had suffered morally during my sojourn in San Francisco, that even now when our fortunes trembled in the balance, I should have consented to become a smuggler—and (of all things) a smuggler of opium. Yet I did, and that in silence; without a protest, not without a twinge.

(From The Wrecker by R. L. Stevenson and L. Osbourne, chapter X. passage 154/155, published 1892)

What does should have express there? Should can express different meanings. I'm not sure what meaning of should fits this context.

Editing:

I've looked "should" up in my grammar book English Grammar Today (Cambridge University Press): It has this:

Should: uses

. . .

Surprise or regret

We sometimes use should to express surprise or regret about something that happened:

I’m amazed that he should have done something so stupid.

I’m sorry that he should be so upset by what I said.

I surmise should expresses both surprise and regret in this context. I think that could make up a good answer.

Answer 1

The Cambridge Dictionary has this entry that seems most applicable:

Mainly UK: used after "that" and adjectives or nouns that show an opinion or feeling:

• It's so unfair that she should have died so young.

From context, it should be clear that the feeling or opinion that the narrator expresses is judgmental of his choices.

It shows…that, even now when our fortunes trembled in the balance, I should have consented to become a smuggler…

The use of should in this way lends a casual wryness to the thought that might be absent if a different definition were used.

• …even now when our fortunes trembled in the balance

This phrase at the heart of the passage, neatly separating that from I should, is what sets the context for the passage. Based on what surrounds it, the phrase suggests that the narrator under normal circumstances would act conservatively when stakes are high. He attributes a shift in his moral compass to be what allows him to behave contrary to his nature. If he were acting in a way that was consistent with his former moral self, he would not consent to become a smuggler, much less a smuggler of opium to which he has a particular aversion.

The last sentence suggests that his passive acceptance without protest is not without pain. Perhaps, this is acknowledgement (pride?) that he was not so far gone that he was numb to his predicament at the time.

It shows how much I had suffered morally during my sojourn in San Francisco, that even now when our fortunes trembled in the balance, I should have consented to become a smuggler—and (of all things) a smuggler of opium. Yet I did, and that in silence; without a protest, not without a twinge.