So my brother has a child with a woman, a little girl. She has custody (duh) and he gets his daughter Fri-Sun every other weekend. Her new husband is a violent narcissist, and has threatened several people, his mother in law with a knife, my brother with a crowbar (among other general threats of violence), a co-worker, + probably a bunch more I don't about. All of this was brought up in court, yet she is still granted custody over my non-violent brother.

Best interests of the child my ass.