1. What was the reason for your wife's leaving you?
2. Try to address the problem first,
3. wife can file case at the place where she is now residing except the complaint u/s498A,
4. If she files any case at Mumbai, you shall get Summons from the Mumbail court,
5. You can file an application before the supreme court praying for transferring the said case from mumbai to Delhi on valid grounds,
6. You can file divorce petition at Delhi on acceptable grounds for which the court will send her summons accordingly.