You do have the ability to recover legal fees if someone has petitioned to cancel your mark in bad faith. In order to have a chance to succeed and let your opponent know that you are serious about protecting the mark, you really need a lawyer. There are qualified lawyers who will assess this risk and let you know the probability of success on the front end for relatively little cost.
It sounds like your are involved in an administrative proceeding before the TTAB, and not in court. Discovery is generally more limited before the TTAB, which generally only has authority over the trademark registrations at the USPTO, such as a cancellation proceeding.
Regarding the fraud claim, in a recent decision from the Federal Circuit, In re Bose, the standard for proving fraud on the Trademark Office was raised considerably. The TTAB has since struck down a number of fraud claims for inadequate pleading. If the petitioner has not adequately pled the fraud allegation with particularity (including that misrepresentations were knowingly made), then you may be able to dismiss the fraud count on the pleadings. A motion to dismiss for failure to state a claim should be filed before the answer (which will toll the time for filing the answer), but may also be filed concurrently with the answer. A motion for judgment on the pleadings may be filed after the answer. You should consult with a trademark attorney about the specific facts of your case.
This response is for informational purposes only, and is not intended to constitute legal advice and does not constitute an attorney-client relationship.