Do you have green card? I think you need to talk to a lawyer.

If you can stay in US legally, your chance of having physical custody of your children is pretty high; your hu*****and need to pay child support. However, lots of states do not allow divorce during pregnancy. You can talk to local woman's group (or your school's legal adviser) for more detailed info. For example, if you or he want to separate now, does he need to move out and pay your rent?