Is There a Better Way to Deal With Domestic Violence?

I was in my second year of college and living in a town home about 10-minute walk from campus. I lived there with two other girls at the time but they were all back at their parents' house for the holiday. There used to be four of us living there but one girl had moved out due to issues with her boyfriend. She wouldn't listen when we told her and we would have to talk to the landlord then. Long story short she ended up moving out and left on bad terms with us. On another side not here I have been physically and mentally abusive relationships before so I understand how things may have been going for her. At this point it was affecting everyone and we didn