Joint custody - abuse question

My friend been violently abused physically and sexually by her child’s father for years. She left him 2 years ago and now has joint custody. She sees her 5 year old son every other weekend because of her ex causing trouble and telling lies about her. She was too scared to leave so she had no reports of the abuse. She also witness him abusing her son and now the exs new wife reached out to her telling her stuff she already knew but saying how bad the ex is abusing the son. New wife even left him.

Would it be legal for her to take her son to a DV shelter on her weekend to see if they can help? CPS and family court don’t do anything useful even after reporting the abuse now of her son.

@kim she has called the police, and cps multiple times. Nothing has been done.