Wiley Miller, the cartoonist behind the popular “Non Sequitur,” told an audience for the first time Monday that he almost lost his livelihood and marriage after he scrawled a vulgar note to President Donald Trump that appeared in newspapers nationwide. The comic that ran on Feb. 10, 2019, was created weeks before on a day like many others since Trump took office. The president had said something that upset Miller, so he penciled the note.