how can he get legal documents to support our family?

There is a way if he still has his visa and proof that he lawfully entered the U.S. Does he have an I-94 card in his old passport? You will need to spend money and quite a bit of it. You will also need a family member to act as a joint sponsor, where you don't earn enough money.

This can complicate or delay the paperwork. Yes, this can get expensive in that you can both end up paying over $1500 without an attorney, where the medical examination and USCIS filing fees are added together. If there are any other complications, you can pay over $2000 and he can be placed in deportation proceedings.

Even if you don't have much money, it makes sense just to schedule and pay for an appointment or teleconference with an experienced immigration attorney. This is much more reasonable and you can get a better idea of what is going to be expected during the process even if you don't hire the attorney to do the work.

This is general information and is not meant to create an attorney-client relationship.