I think Sarah's litmus test is a good one, but I also think that volatile marriages make even more volatile divorces. He seems to want to make things better, as long as you don't stay with status quo, it may be worth trying, but by the sound of your current relationship (you're both in the blame mode) you need some kind of outside help.
You've actually articulated some real serious issues in your past that need to be dealt with if you really want to break the cycle. Kids can be a good motivation for improvment in our lives. Good luck, I commend you for seeing the need to change your situation. Sometimes divorce is required for change, sometimes not.
With little real knowledge of the situation I would hope that fixing your marriage is possible, but you are in the best postition to judge that.