Had a similar thing happen in my last place with the guy above me. Heard his gf going crazy, yelling throwing shit only to end up in the hallway crying. I asked if everything was ok and she just states at me then went back in the place. I never saw her again. It didn't sound like he was hitting her just her being a crazy bitch (kept hearing him say calm down and stop. She was throwing shit and screamed like she was dying only to have him say calm down) I didn't do anything after I talked to her for that moment in the hallway since after that everything was quiet. I would have done what you did in your situation.