Excerpt from the "Catcher in the rye":

He used to be just a regular writer, when he was home. He wrote this terrific book of short stories, The Secret Goldfish, in case you never heard of him. The best one in it was "The Secret Goldfish." It was about this little kid that wouldn't let anybody look at his goldfish because he'd bought it with his own money. It killed me.

I'm struggling with a clear explanation to provide my students about "it killed me". I can understand the meaning from the context, but I find it hard to provide a clear definition.

The way I see it, it means that the main character really liked the book so much. But that's not the exact meaning I'm looking for.

Any help?