Since you are already worried by the fact she is a graded black belt in some shitty 'martial art', she already has the advantage. If I was in your position, my gameplan would be to avoid getting hit- I've sparred with black belts, male and female, and believe me, they can hurt you.
Easiest ways to victory:
A- Try to KO her, but risk being kicked in the head by a woman
B- Try to copy your hero(Chuck Norris) by roundhouse kicking her, but risk getting kicked in the head by a woman
C- Take her to the ground, but risk seeing how dirty women actually fight
D- Sneak up behind her the day before the fight and hit her with a baseball bat, but risk being arrested for attempted murder
E- Push her down a well, and risk.....nothing. Nobody will know, and you won't have to tell anybody so this seems to be the best strategy.