Hi again,
Just want to say I agree with barbie whole heartedly about not ending the relationship quickly. You need time to take a good look at what is really going on, both the Lundy and Beverly Engel book will help you do this. I left my H several times but always ended up going back because like you I didnt want my kids to have a broken home and he wasnt abusive all the time, so I couldnt recognise how bad things were. After I read the Lundy book it took me 5 months to decide if the relationship could be saved or not, in then end I left even though I have a 3 year old and am 5 months pregnant. I finally realised that the damage was greater than I initially thought, to both me and my children. (have to say, I am doing very well and am happy now!)
So, you say you dont know where to start. Buy the Lundy book, read it, without mentioning it to H, and spend some time evaluating your relationship in terms of what you've read. Only you know how bad things are and if things can be saved, but what you must do is learn about and fully understand how abusive behaviour works so that you can recognise it for what it is.
One example is that your H has now gained a special privilege, he no longer has to do teeth brushing chores. THIS WAS HIS GOAL ALL ALONG. He has used very nasty tactics to achieve his goal, by emotionally bullying you, and physically bullying his child. As barbie says engaging him is pointless, he will not respond to reasonable arguments ("what you did was wrong because it wasnt in the childs interests") If he were capable of that he would have had a rational conversation with you in the first place about how he didnt want to brush teeth any more because its frustrating and difficult. Instead he chose to use tactics that ensure success: bullying and aggression. If this is a pattern of behaviour that happens regularly, he always comes out gaining freedoms, power, privileges, and you always end up doing more than your share, taking the blame, being wrong, then you are being emotionally abused. There is plenty that you can do to change things so have hope, the first step is to recognise what is going on. xxx