The correct answer is that the part that is ironic from this statement is : "Sickeningly comic aspect of an unfunny situation."
Explanation:
This is ironic because in a sitaution that seemed funny or wwas supposed to be funny it was the complete oposite. Sometimes irony can be very direct on the conflicting definitions of a few words.
you didnt add the excerpt but the definition of idiom is a group of words established by usage as having a meaning not deducible from those of the individual words or a characteristic mode of expression in music or art.