"Trying to decode why he is the way he is. Why he's still calling, why, why, why?"
Because he's an alcoholic.
And we've all felt stupid and mad at ourselves for getting involved with them and even worse for staying involved with them. Be thankful that he is your ex.
What has worked for me is to step into my own life and let him and God take care of him. I'm doing the things I enjoyed before he and I met and I'm spending time with friends that I had before life became crazy. I'm back in church. I went to a counselor. Also AlAnon has been great for me. I've wanted ME back so bad that I am doing everything I know to get me back. And you know what...it's working and it feels great! If my XAH wanted to get better half as bad as I do then he would be doing the same thing.
You can't do anything for him but you can take care of you. And once you start doing that you will begin to feel more positive. Good luck to you.