1. You shall have to collect evidence of her cruel acts on you by audio/video recording her conversations and abuses.
2. Thereafter file a divorce suit in India at your place on the ground of cruelty submitting the evidence in support of your allegations. Divorce in India can be filed only on grounds acceptable by Indian law like cruelty.
3. You can also negotiate with her for jointly filing mutual consent divorce petition on agreed terms which will be disposed of with in 6 & 1/2 months from the date of its filing.
4. Lawyer's fees vary from court to Court, Lawyer to Lawyer and Place to Place. In Kolkata, a suit can be filed by paying legal fee of rs.40 K to Rs.50 K and the appearance fee will be around Rs.3 K.
5. In filing MCD, there will be hardly two appearances and in contested divorce cases, there will be multiple appearances spanning up to 2 to even 4 years depending on the period for which the case runs.
6. If you file divorce suit, she might lodge false police complaint u/s498A of IPC alleging dowry harassment, DV case and also application for maintenance from you.