Don't confuse zingers, or "truth darts" with your confrontation speech. You don't need a PERFECT script here (altho the better it is, the better, obviously) -- just "speak the truth, in love" and you'll do fine.
Barring nasty interruptions from her (at which point you should end it, as discussed), it should be short and sweet -- maybe 2 or 3 minutes long. You are now a man of ACTION, not of WORDS anyway, and this confrontation is merely to "go on the record" with her so that she doesn't misinterpret -- nor underestimate -- your silence following your infidelitus interruptus.
Cover the main points, speak the truth in love, show her you can look her in the eye and deliver these things without tearing up and without angry outbursts, and get in/get out, like Ali.
