Girlfriend's room mate threatens her with shotgun

A few years ago, when I first met my girlfriend she was living with someone who is really crazy. Think buffalo bill (call him bill) from silence of the lambs.Well, when I first met her she was living with him and his boyfriend, and she invited me over to watch some Netflix. Keep in mind that "bill" owns the house and he's renting a room to her.For reasons that I still don't know, he just never liked me at all. I think it came down to me having a beard (not joking)Anyway, bills boyfriend comes up to the room, asks my girlfriend to talk and they start arguing. Turns out I'm not allowed to be there, but technically renters can have guests in my state (she went to court and won over this)the next day we go to get her stuff and someone video records bill saying "I got a fucking shotgun and I don't give a fuck" about how my girlfriend got a tone with him and how she can't be evicted in one day legally speakingAt the time, I was not a gun owner. But now that I am, I've been thinking about the situation and how I would have handled it. I think it's complicated because it's his house but that sounds like a threat to me.(a note: the video was not allowed in court because it was done without his consent, we tried going to the police too, same deal)How would you handle this? Could I have brought my ccw into the situation if I had it? via /r/CCW http://bit.ly/2Zv0pxF