I have been married to mny Chinese wife for about 3 years. She has been in this country (USA) for 15 months. I am sure she used the marriage to gain entrance to the country. We are physically separated but she demands money. I want a divorce and I want her to go back to China. She says I am screwed and must support her from now on, even if we divorce. What are my options?

All you should do is file the divorce. If she is having a conditional green card and divorce before filing removal jointly, she will be subject to deportation though the process may not be immediate. If you signed a prenuptial agreement prior to marriage, she may not be able to claim any spousal support.

Do not report to USCIS or ICE, because when you report the authority with expression of anger, if your spouse claims there was domestic abuse, your report will definitely support her statement and it will look bad on you. If you really feel like doing it, get help from an attorney.

File divorce... and move on.