DV is one of the biggest blights on society. End of. It disgusts me in every manifestation.
First of all, well done. I know you say you feel traumatised by this, and it sounds like you should probably quite rightly feel this way given what you have seen. But, I would take it from it the fact that even though what you have seen is harrowing and shouldn't have happened, you may have well prevented something far more serious from happening.
It's a pretty brave thing to wade into the middle of a domestic. Especially one which sounds as heated as this one sounds.
Someone has mentioned on here that the situations can be volatile. Someone else has mentioned that they can be a minefield. They can be the former, and are almost always the latter.
Someone has said that the person who is the victim has no gumption. This is something I must contest. I deal with countless situations akin to the one describe each and every week, and it really just isn't that simple. I think your post wasn't perhaps as well thought out as some of your others have been?
This sums up why pretty succinctly, and it's a great post.
Unfortunately that sounds a bit as though staying with an abusive partner is a kind of weakness. It's very difficult for anyone who has never been in that kind of situation to appreciate just how subtly an abuser can exert powerful control, psychological as well as physical, over an otherwise normal, sane and balanced partner.
I'm 6ft1 and built like a wall, and make no bones about telling people how I was in a psychologically abusive and controlling relationship for almost 4years, before I had the knowledge, the awareness and the realisation that I needed out. It's not easy to break the cycle and to finally remove yourself from the situation.
Once again. OP. Well done. You out yourself into a situation which could've been a volatile, dangerous, minefield at great personal risk to yourself, and have probably stopped someone from coming to serious harm. Well done.