You are making a mistake with meeting her in person...
You are opening yourself up to a big letdown. No matter how much you want to say differently, you have already tried to turn this meeting into a "she wants to reconcile talk"..
Your BEST move here is to CANCEL the meeting. YOU cancel..
Get some nads here... YOU call her up and you tell her that you have been doing some thinking.. and YOU have decided that you really don't think you need to meet and that if she has something to tell you to just say it over the phone. Tell her you are very busy...
You need HER to think that you are NOT interested in a meeting and that anything she has to say can just be said right over the phone. Here and now...
Quit playing into her drama...
IF she wants to get back together, then cancelling the meeting is even smarter for you to do. It will make her PANIC even more. If she doesn't want to get back together, then you haven't wasted YOUR VALUABLE TIME...
Men who act like you do regarding meetings and dates with a woman who has dumped then, don't get the woman back. Stop dancing to her tune, and start her dancing to YOUR TUNE..
(by the way.. good job on bringing OW into the picture. Keep her in it) Tell your WS that you don't think it would be wise to meet her because you are "kinda seeing someone".. then tell her no more...be vague... stay vague... ( I suspect she already knows)