First, what ever the personality will not be important; to marry with one who just devoiced - maybe they love each other right? which can’t prove she was wrong doing.
Second, this lady was underpaid for a long time.(You may think would far more than she got in China)
As you said:
几年来公司没有按办H1B上的金额付她,……给她写了许多工资的假证明,……同时发假的工资单.
告公司和老板欺骗大众 ……找公司的财务漏洞
Those are illegal. If she could prove ( the past pay checks with those 工资的假证明). Any lawyer will help her win the case easily.
some one (you hu*****and most likely) in the co. will be sent to jail for sure.
The best way to do is to ask her drop the law sure, and the co pay what every she should get as all other bookkeepers in US.