Whoa!
I think your friend is yanking your chain. A US citizen cannot revoke his wife's green card by sending it back to USCIS saying he's "no longer filing for her". First, the US citizen does not apply for the green card - the immigrant does. The only thing the US citizen can do is withdraw the affidavit of support, and once the AOS is approved and the green card is issued then it's too late to withdraw the affidavit of support. Second, he could get into SERIOUS TROUBLE for sending her green card back. It's not HIS green card, and he has no business doing ANYTHING with it. Third, adultery is not a violation of ANY aspect of immigration law, and is NO basis to revoke a green card. Fourth, even if they thought that SHE had voluntarily surrendered her green card (which she could certainly do), they would not have sent ICE to pick her up. She would have been permitted to leave the country voluntarily.
Your friend's story sounds like something a jilted husband of an immigrant wife might fantasize about doing, and might even believe that he could do, but it's highly unlikely it actually happened like that.
NOBODY deserves this treatment.
I'm not going to tell you what to do....but think about how long you want to stay in an environment (esp with the baby) like this.
