In order to take back your power, you need to detach, leave him alone and live your life as if he is never coming back. You have to think of him as being on a very long, round the world trip or even deceased.
You have to become very independent, do things for yourself, and find ways to keep busy. Make a list of those projects that you've put on the back burner for a long time and start doing them. Check them off as you complete them. Do not rely on him for anything because he's a mess.
The anger is guilt. The anger is what fuels his justification for leaving you and your family. It has absolutely nothing to do with what you did or didn't do. It's all about him and his childhood issues that need to be resolved.
Anger is part of the grieving process and yes, you are allowed to be angry. However, come here to vent and find a nice old pillow and beat the stuffings out of it when you are angry. If you become angry when he's around, walk away, go to another room, or go for a nice long walk. The more you fuel his fire, the longer it will burn.
You will learn the steps of the MLC dance, one at a time. Learning the art of detachment takes time, but you will learn how to do it. The first step is learn not to take what he says or does personally. The second step, try not to react or defend yourself. The third step is to learn to rely on no one but yourself, family and friends, for his is not going to be reliable for a very long time. The fourth step is to learn to live your life to the fullest and be the best parent you can be to your children.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.