Well, I think your instinct that you need to take the high road is correct, regardless of the pain it might cause you, unless you think you might actually get in a fight with her.
My .02 is to send your W an email - tell her its important to D that you both be at one of these events ( and maybe suggest one that is at least a couple weeks away to give you more time to emotionally prepare)and that you are prepared to spend an hour in the same room with her for D's sake and are not really expecting to interact.
