When it comes to such situations I always think worst case scenario, dark things come to mind which make me second guess. I've always had this paranoia way of thinking, there's a lot of fear inside of me somehow.
And when I read what MC is going through and his decision on what to do, well I couldn't really say that it's the right thing to do or not. Because me personally, I think about what could happen if he would just do that, knocking on the door and all that. It's obvious that the guy who's beating his wife etc. is not really healthy in his head, so if that guy finds out who calls the police every time and is the reason for taking his wife/child away from him, just imagine what plans he maybe would make to make MC's life miserable? It's dangerous, because that option is open, we don't know. So if MC wants to do anything, I would advice it to do so anonymously, that's my take on it. Could be wrong..