A literary dilemma

I have recommended some novels by a particular author to a couple of friends. Call them books A and B. A ends with the protagonist arrested by bad guys, leaving you with a feeling of dread, that he will be tortured and die. Book B was written a few years later and I happened upon it not knowing that it had anything to do with Book A until I began to read it. It was brilliant. Had I known Book A was going to have a sequel, it would have changed the way the ending affected me.
I wanted to make sure my friends read A and B in that order, but I didn't want to "spoil" A by letting them know that B was a sequel, so I suggested they read A, then C (a book by the same author set in the same general period, but not related), and then B.
One of the friends has just read A, and liked it very much. He is going to read C. He will probably think I am an idiot at some point.
Is there another way I could have done this?
Now another problem I see is that if any of you want to read the books that have caused me such anxiety, I may have ruined it for you.
My head hurts.
I wanted to make sure my friends read A and B in that order, but I didn't want to "spoil" A by letting them know that B was a sequel, so I suggested they read A, then C (a book by the same author set in the same general period, but not related), and then B.
One of the friends has just read A, and liked it very much. He is going to read C. He will probably think I am an idiot at some point.
Is there another way I could have done this?
Now another problem I see is that if any of you want to read the books that have caused me such anxiety, I may have ruined it for you.
My head hurts.