Mom has been abusing my disabled father. What can I do?

My mom no longer speaks to me as I would not tell a therapist my father was crazy and help lock him away. She has not been taking care of him or making sure he has his therapy and his health declined and was taking to a er and nursing home to rehabilitate . He cornered him into signing poa a couple weeks before as he was totallyt dependent on her. She is the crazy one. Now she has discovered she only has to give him $52 a month and can spend his navy pension and social security. She is selling all his belongings. He could come home after rehab and a prothetics could be obtained through the va. I know he is safer in tis nusing home. She has message when speaking to me previously she wanted to kill him, made him sleep in floor when feel from wheel chair, crawl accross floor to get in home ect.. Both her and my 27 year old sister live in home and no excuse. He has contacted me several times as he is very upset and depressed . Not metally handicaped at all. He could be in an elderly apartment and control his own funds. He nor I can afford an attorney and I dont know how to advise him or what to do?