Subtitle formatting

Thanks, I’m finding this quite helpful. If you could bear with me, I just have one more subtitle pair that continues along this vain but I think might be a little different:

“I don’t think one second of this is funny -” (tersely and with definitiveness)

(extended pause)

- sir." (as an afterthought with a touch of sarcasm).

Might an ellipsis after the first subtitle be too contradictory with the speaker’s tone, while, conversely, an ellipsis added before “sir” clarify that it’s an afterthought? Or would there be a better way altogether to punctuate this subtitle pair?