I've been there and understand that you want to be absolutely sure you've done everything on your part to stop it happening again, and that you try and understand why, and because you love him you want to accept that you provoked him, and that the thought of getting police involved and leaving seems so dramatic.... and all the other things a person does to try and make it better (because going to the police, leaving etc., feels like its going to make things worse).
Its all bollocks Lauren believe that.
There is no provocation or stress in this world that makes it acceptable to beat someone, deny them chance to escape or keep them under house arrest. You may understand why, but that does not justify the action. You need to get ANGRY. You need to get angry and develop the mind set of "How dare he do that".
I cannot tell you what to do, you won't do anything until you believe that no matter how much you pushed his buttons his behaviour was unacceptable... he always had the choice to walk away, hit a wall, but he chose to hit you.
There is time for compassion when you're safely away from him, when he's paying the price of his actions, you cannot afford to be compassionate and forgiving now.
I don't think YABU to involve your friend, this is what friends are for, the rough and the smooth. YABU to wait until next time. If you can, plan your escape now, make that your priority, for your children if you don't feel worth it yourself (you will do one day I promise). I would recommend turning the pc off and leaving now, with nothing but the clothes on your back - you would survive - but also understand the reality, the massive challenge that is.
My DV happened years ago, over a period of 5 years. I justified it, forgave, had compassion, empathy, I blamed myself for pushing his buttons... it is all bollocks. It has taken me a long time to believe it was. I'm now in a loving relationship with a decent human being, I push his buttons, I'm unfraid to speak, we row, and in 13 years he's never touched me. He's not a saint, he's NORMAL. The situation you are now in isn't and cannot be justified, even if you feel you can understand it.