separation and child living conditions

What is the name of your state? Texas

My brother and his wife were living with her mother and now they are separated because his wife made him leave for another man to live in her home. My brother lives with me now but doesn't know the first thing to do. He wants a divorce but can't afford it. Also, his daughter is involved and he wants custody. What are his rights? Is there anything she can hold against him? He does pay her money every two weeks. Please let me know any information available for him. Thanks.

He needs to hire an attorney and file for divorce and custody, that is unless he can do all the paperwork himself, he understands family law, and can represent himself.