1 What should I do? Will I be arrested in India?
This is not a crime committed in India that they will arrest you. This is crime involving loan and default in repayment so they have to initiate only legal process.
2. Can they send goons and get me killed or break my bones?
They cannot take law into their hands. If you receive any calls, record them and make a complaint against the caller with the local police for initiating legal action against their threats.
3 Please advise on the legal aspect of this harassment.
If you are ready to make the payment, you may negotiate the amount, if they dont agree, ask them to proceed legally and not to handle illegal things against you or your relatives, failing which you have solutions to tackle them legally.