Legal help in Army/S.I.L is Trash!!

So let me just start by saying I’m trying to help my brother. He has been deployed for the last 9 months in another country. His child is 1.5 years old. His “wife” is GARBAGE. She had an affair and is in a relationship with this guy publicly and now she thinks that since my brother is in Another state where he is stationed and she is in another state that they are separated. Neither of them have any paperwork at all stating they’re not together. She also told my brother a few weeks ago that his son might not even be his. So she has kept his son away from him completely and won’t even let my brother talk to him. She is making her son call my brother by his first name instead of dad. She has blocked all of my family and changed her number so we can’t see him at all. Is there anything my brother can do?? He went to legal but they told him he has to go to an outside attorney because it’s also a custody battle. Well every attorney he has talked to said he has no chance of getting his son because he has been deployed and the wife has taken care of him. First off, she had cps called on her not long ago because of suspected neglect/abuse. My brother just wants full custody of his son and to get away from the trash he married. Also she got a home from them in Texas and left it in such poor shape that my brother can’t believe she let her son live in the conditions. I’ll post photos below. She took the keys to his truck, the house and she took his pistol. So he did file a police report for those things. Has not received them though. He just needs help and idk how to help him.

My brother FaceTimed her and his son called him dada and she corrected him and said no that’s not your dad.

She let him eat hand sanitizer so he had to be hospitalized.