My sister is being..?

My sister and mom are having problems with my sisters ex boyfriend. He is repeatidly slashing their vehicles tires, being physically abusive to my sister (as well as emotionally and verbally abusive), he is exposing my sisters two yr old daughter to violence, he has become increasingly violent and dangerous. I... show more My sister and mom are having problems with my sisters ex boyfriend.
He is repeatidly slashing their vehicles tires, being physically abusive to my sister (as well as emotionally and verbally abusive), he is exposing my sisters two yr old daughter to violence, he has become increasingly violent and dangerous.

I am not sure, as her sister and as my moms daughter (since he has broken into her house and frightened her with that stuff as well), that I can report him or their situation to a domestic abuse hotline.
I am very worried not only for my neice, but also for my sister and my mother, who takes care of my mentally disabled brother full time.

If anyone has any kind of advice, phone numbers, places i can go to report this stuff, please, feel free to suggest them.
I live in Missouri.
2 answers 2