Thanks so much everyone for letting me volley this question to you. I'm trying to be as comforting as possible and I wanted to see if my approach passed your smell test. Your commiseration and kind comments are heartwarming.
I really like knute's suggestion to reveal the ending and then work through the story to understand how the tension was resolved. I think DS easily gets swept up in the momentum of the story and is heavily immersed in perspective-taking while we read. He often animates his toys with his own thoughts and feelings (e.g. "Excavator is bothered by that noise", "Monkey prefers to drink almond milk"), and I'm seeing him take on the persona of characters in the books as we read.
For instance, in a storybook we read about robots yesterday, DS became upset when a robot was kidnapped by a silly mad scientist. He (DS) said, "I don't like that. I'm scared." So, the concerns range from the more remote and scary, like being kidnapped, someone special going missing, or parent-child separation, to the more quotidian, like not being able to get out of the bath tub. He definitely doesn't have the maturity to assess the probability of remote tragedies.
One thing I've been trying to do is turn scary moments into funny offshoots of the story. So, for the bathtub, I asked DS if he thought Paddington would be upset to be stuck in a big vat of marmalade (ala Winnie the Pooh getting stuck in the honey tree). What if he had a trapeeze and could swing out of the tub? Or what if he overfilled the tub then floated out of it? Then I act out these scenarios, sometimes I draw a picture of the silly alternative ending, etc. Let's just call my visual and dramatic arts skills somewhat subpar.
And re: tearjerker books, my top-3 avoidables are "The Velveteen Rabbit", "Love You Forever", and "The Giving Tree". Those are way too poignant to be read with dry eyes. I don't remember the end of "House at Pooh Corner" well, though I do remember finding it sad as a child. I have my fair share of emotional OE.
