Wellll what a mess.
For starters, I take a dim view of blackmailers. That is precisely what she is doing..blackmailing him.
He has options as long as he has a backbone. He can report her illegal status and do his damndest to get her deported before the child is born. He can also wait till after the child is born, demand DNA tests and then report her illegal status. Baby stays in the U.S. because it will be a U.S. citizen and he can take custody of it. He needs to call ICE asap.
He can't persue anything till parentage is established. If she tries to file for welfare, then welfare can demand the paternity tests. She cannot just blatantly deny him visitation. Although it most likely will take an attorney to force her to comply with visitation through a court order. If he goes that route, he could just petition for full custody. However, YOU have to be willing to also take care of that child. Is he 100% positive this baby is his? Many a man has been conned into false fatherhood. So be careful on that part.
In case you are unaware of this....it is illegal to marry someone just to gain citizenship or permenent residency status.
Check with your local laws about recording her phone conversations. Your finace may record her conversations as long as there isno one else involved in the conversations. If she aaaadmits to her scheme...play it back for her, then advise her the recording will be turned over to the authorities. Not only for the blackmail attempts, but also trying to coerse him into a criminal activity...ie: illegal marriage.
I would not dally on this issue. He needs to take a proactive position to back off her blatant attempts of further criminal behavior. Of which he does NOT NEED to be a party to.
Good luck on this....:)