
Ok, now this is exactly what truly bugs me. Because of these types of girls (or guys in other cases) that just want to misuse people to immigrate the real honest legal ones have to go through the hassle of the long process and so on. Not nice, not fair at all.
I understand completely your sadness, anger and your frustration. I am the immigrant, my hubby is the USC. Everybody has problems at one point or another in their marriage but when a marriage ends it already hurts more than enough without all the problems added onto it by the immigration process.
What I suggest:
1. IMHO I would have never given her green card. I would have gone to the local USCIS office (infopass) and presented the case there before giving her the green card. If she wants the green card let her get it from there or I will give it to her IF AND ONLY IF the officer at the USCIS office TELLS ME TO DO SO. But I would also record the name (full name of the officer telling me to do so) and present that in my case that I would sent to the USCIS reporting the whole case, also stating time and date and including a copy of Infopass appointment. BUT since you already have given her her GC still make an Infopass appointment and ask them what you should and could do about this. Present all you have so far and all you have done about it so far. Again, record name of officer etc. etc.
2. Hire a PI. Let the PI do the dirty work for you. You relax. The more you wind yourself up she will have won, rejoicing about your pain and sorrow. Yes, it isn't cheap, but a divorce or a case ten years down the road will never be cheap either, let's just get it over with as soon as possible. Talk to a couple of PI-s and see which one is the most reasonably priced but still is very professional and friendly about it. Why a PI? Because they can easily go places you can't at times you can't. Plus it will become hard evidence supporting your whole case instead of letting it stay "hearsay" as it now basically is. I know it is hard for you. And most of all... you yourself stay clean, no going to other women, doing drugs or becoming an alcoholic, never abuse her no matter what. Do not give her any reason she could use against you in court of law. Again I am so sorry, I know this is hard for you, but be very strong for now otherwise she will "win".
3. Do I take your side 100%? No, I am sorry because I do not know you well yet and because every story has its two sides. BUT I BELIEVE YOU because this has happened too many times to a lot of my USC friends. And I knew both sides of the stories sadly pretty well.
4. Divorce her as soon as possible... AFTER YOU HAVE ALL THE PROOF FROM THE PI. She will get into a lot of problems going through the interview if you also have papers stating you filed for a divorce already based on whatever you can find out. This is why I am not talking about it all as a fraud rather more how to handle a domestic dispute. If you have all the evidence then and only then your marriage and her intentions will prove itself to be a fraud anyways. Simple, right?
5. Go to the interview. Not because you have to be afraid of threats, never be afraid those. How could she force you to go anywhere? Blackmail? Again, if you don't do anything wrong she cannot blackmail you in any way. Get a gun if needed and if you are comfortable with it. Only idiots would still come at you if you have a gun to defend yourself. Do not become trigger happy 'tho... Be very responsible. NEVER THREATHEN HER or anyone else WITH IT EITHER. Don't feel bad about having to protect yourself if you feel the need to. Stay with friends and family if needed. She might not hurt you herself, but she might misuse another guy and his friends to hurt you. Go to the interview to present your case to the fullest. It will be a wonder if the immigration then doesn't immediately deport her altogether.
6. Be strong. Do not go soft on her. Flirting, crying, begging, kissing feet... whatever she might try to woe you... Don't fall for it. Don't sleep with her is another good point. She could and would misuse that against you. Worst to worst if she sleeps with the other guy and with you too she can say it is your child. Then what? DNA tests? Abortion? More trouble than it is worth.
7. Last but not least... BE VERY SURE ABOUT ALL THIS. Be prepared, be cautious. Be wise, stay as calm about all this as possible. Don't become paranoid. Again, I know and understand how it must hurt. If there is any doubt whatsoever in your mind then don't do anything drastic untill you have all the facts straight and you can be sure about it. Love is blind people say, in a way it is true, so open your eyes. Stay yourself, be friendly but strict and blunt.
Am I being radical/ weird/ paranoid? No. I don't care what others might think. But I have been through hell on earth in the past in a lot of situations and conditions that others don't even want to have nightmares about. So I learned from my own experiences and from others to be well prepared. Mean? No. Just blunt.
If you are truly honest about all this... believe and you will find another girl somewhere somehow, someday that will love you for you not for America. I came for my husband, not for America

so much that it is my hubby that is "forcing" me to do the the whole immigration process. I filed the AOS almost 180 days after my K1 expired. I did not even want to get married as soon as I came, we waited untill the last two weeks... WHY? Because I want him to be sure. I want me to be sure. A marriage is hopefully untill I die and beyond so I would never want him or myself to feel forced to get married or stay married just because of fear of being deported. I just comply because it is the only way to be able to stay with him and if it makes him happy why not, right? I love him more than my own life. Am I truly this light about all this?

YUP. Ask my hubby and my friends
Sincerely,
Gwyneth