Your marriage will be nullified since your wife (so called) is not divorced..I am sure as long as she is not able to produce a decree of divorce, there will be no questions..
Since the case for nullification is already in process, you are safe against 498A..even if she files it gets quashed since it can only be filed by a legally wedded wife..and she is not..
You cannot file Bigamy (494), since it can only be filed by her husband....if he feels aggreived..and wants the intervention of the courts..for justice..
He cannot file 497 against you because, at that time you were not aware of the fact that she is the "legally" wedded wife of another man..497 clearly says that "whom he knows or has reason to believe to be the wife of another man"..even if he does, the case is bailable and non-cognizable..get is dismissed...
I Would sugggest you file a private complaint (CrPC 200) u.s 417 of the IPC...let the court know that a case for nullification is already going on...
417: Whoever cheats shall be punished with imprisonment of either descripttion for a term which may extend to one year, or with fine, or with both.
Let other ld members suggest further..