The structure looks like this:
And so Cath began telling me her tale. Which turned out to be grimmer than I'd expected.
"I've been suffering from migraines ever since high school. I'm not talking about those sissy tickling behind the eyes, but really strong hammerings—so strong, in fact, they sometimes make me want to split my head open and scoop out my brain...
"And that's when it came. It began as a tingle in my temples that grew stronger and stronger, until it became a tightening pain. Like the walls of my skull were closing in, squeezing my brain...
Chapter 11 consists mostly on Cath telling her story. The protagonist interrupts only occasionally:
I stared at Cath, astounded. "What happened then?"
I mulled this over. I'd never thought about nature that way. Imperfection. Was that the reason things like cancer, allergies, and other human afflictions existed? How about death?
Not sure whether I should remove the quotation marks or the parts where the protagonist interrupts.
What do author usually do in these cases? Which is more pleasant to the reader?