I moved from Employer A to Employer B On H1. After serving Employer B for 7 Months , I moved to Employer C. Now Employer B owes me few weeks of Pay as final settlement. He even stopped last week salary. He is now asking me to pay(consent for deduction from final settlement) for the H1B Amount he invested and threatening me that he will not support when asked for employee reference when Company C files GC. He also says he will give a negative feedback. He even negotiates with me to pay some % of Amount.

Could some one please advise what needs to be done in such cases.

When Employer C Files for my GC , is it required to have any kind of employment letter/employment reference from Employer B ?

Im Not going to pay him the amount he asked for , he might not give me any relieving/employement letter too.