1) your best option is to file for divorce on grounds of mental cruelty .
2) you should install CCTV cameras around your parents house .
3) post security guards around house .
4) record all threat s received by your parents .
5) your parents can file complaint of criminal intimidation against them
6) in the alternative tell your parents to sell their house and ask them to stay with you in USA
7) be prepared that if you file for divorce your wife will file false cases of 498A / Dv against you and your family .
8) in such a case seek anticipatory bail from session court . as per recent SC judgement it would be easier for you to obtain bail
9) dont bow down to her black mail tactics