If these charges are false, Cain has to take this woman on and sue her. If the democrats will falsely accuse in this manner and get away with this behaviour without being challenged then the gates are openned on all and any republican, candidate that comes along. Cain has to do more than just deny. His campaign has to sue her and get evidence that she is working for someone in order to ruin his run for Presidency.
Filing a lawsuit now could force her to come clean.