Question

Which parts of this uses irony?

"Come," I said, with decision, "we will go back
You are rich, respected, admired, beloved; you are happy, as once I was.
We will go back; you will be ill
the cough's a mere nothing; it will not kill me. I shall not die of a cough.
"True–true," I replied; "and, indeed, I had no intention of alarming you unnecessarily