1. The CEO cannot unilaterally change the terms, but if the same was reduced to writing and you both have agreed to this change then it can be a mutually agreed change, by which you may not be able to claim it as breach of conditions of the agreement.
2. You said that it was agreed to settle Rs. 2 Crores to break the agreement, which was again a mutually agreed condition, however if this agreement was not reduced to writing, and the original contractual agreement or conditions only shall prevail then on the basis of the completion of the initial lock in period, you can tender your resignation or offer to quit on the already agreed terms.
If the company is demanding this amount in excess to the agreed terms, you may refuse the same and challenge their claim ibn appropriate legal forum on merits.
3. If the CEO had committed the said offence in India then you can very well take up the case through an Indian court, or you can pursue the matter through the laws governing that country to which he belongs.
However you may have to exercise caution because you had failed to take any legal action when the incident took place but now your intention to take action on these issues may not be maintainable considering it as an after thought action since they did not give in to your demands.