My roommate is so loud what do I do?

We live in 2 studios separated by a thin wall. She brings her boyfriend home at night and makes a lot of noise. I'm a student it's very difficult and she knows this, in the beginning she was considerate but now I feel like she hates me! I'm scared to tell her anything and I've been letting her walk all over me but it's getting too far! She is really aggressive and her boyfriend brags about hitting and abusing girls so I'm afraid to confront them at night. I want to cry. My landlord knew her before I moved in and she told me that she's the sweetest person, I feel so betrayed!