Job agreement period

Hi, In October 2019 I joined a company. But few months after joining they gave me a new offer letter with some new terms and conditions related to agreement period. As per the new offer letter i can not resign before 3 years. But there is nothing mentioned related to consequences if i resign before 3 years of joining. They asked me to sign the new offer letter or the employer won’t be able to continue my employment. I signed that offer letter in the fear of being jobless. Couple of months ago i asked them to negotiate the agreement period because i might not be able to continue after my marriage. But they refused my request. After that incident the country head/ owner of the company started insulting me in front of other people because i was not able to focus on my work, because of the mental tension i was having. When i asked for solutions he said leave the company. Since my agreement period is not over yet as per my new offer letter, do they have right to terminate/ fire me or ruin my background varification or will they give me relieving letter/ experience letter?