Advice

My bf has a 5 year old boy and him and his ex never had a rearranged custody through court . His ex is very unstable and has been in and out of the kids life since a baby . She has a bf and he provides for her and her other kid and their boy would go over there at their place on her days with him . For the past 2 years her and her bf have a toxic relationship they argue a lot and they physically fight each other but ofc the bf is a man so he hits her pretty bad . Their son has witnessed that but my bf would take him for a couple extra days and then he would go back but this has happened multiple times. Well now the son is old enough to see what’s going on and he has said he doesn’t feel safe around her bf . Cops were called at her house in the most recent fight and she took back the charges but cps was involved too and spoke to their son and he told them everything and he doesn’t feel safe around the bf . The mom now wants back her son and my bf refuses to bc she is not pressing charges and she’s refusing to leave her bf . My bf is planning to take her to court bc we don’t want him around that kind of environment. Are we wrong for that ? What can happen during a domestic violence situation where kids are involved and the mom refuses to change anything?