What does the speaker mean by saying "I didn't think so"?
Hi guys,
This is an exchange from a novel. Could you please help me understand 'I didn't think so' said at the end?
"No, she did not send me here. I sent myself."
"I don't understand."
"She stayed with me at first, but she missed him. It made her unhappy... so I decided it was time to spend some quality time with Charlie."
"But now you're unhappy."
"And?"
"That doesn't seem fair."
"Hasn't anyone ever told you? Life isn't fair."
"I believe I have heard that somewhere before."
"So that's all."
"You put on a good show. But I'd be willing to bet that you're suffering more than you let anyone see. Am I wrong? I didn't think so."