1. You are calling her as 'Ex' when she has not been divorced by you with a decree of divorce by Indian Court,
2. However, you should come to India and avail anticipatory bail otherwise warrant of arrest mightbe issued against you calling for your extradiction,
3. Prefix a lawyer from Australia and come to India while applying for AB,
4. Now a days it is not difficult to get AB against charges u/s498A of IPC,
5. Once you get AB, contest the case filed against you fittingly through your lawyer,
6. Afterwards you can also file a petition before the High Court to quash the FIR filed against you.