Selfishness + wtf?

"She stirs! Here's life!
Return, fair soul, from darkness, and lead mine
Out of this sensible hell!"
(IV.ii.344-346)

After his discussion with Ferdinand and realizing that he had just done a favor that would not be repaid, Bosola seems to regret having the Duchess strangled. In this particular line, however, I cannot really tell if by "sensible hell" he means the magnitude of his repentance, or if he is more upset by the fact that he is regretting his action (thus being sensible) and does not want to? In other words, is he upset by the fact that he has seemingly been struck with some sense of "morality"? Granted, I don't think he is upset about the Duchess's death, but rather that he allowed himself to be fooled by Ferdinand. His vulnerabilty at this point is why he is so upset over having her executed.

Also, Cariola was pregnant? What/how/by whom? I was so confused by that...