Oh my--- been there done that. It's amazing how far we go to hang on to a relationship. It's amazing how easily we are made to feel that the abuse is our fault. It's amazing that we continue to love. I have no other reason than biology in general. Women have a double whammy against us. We have hormones that make us attach to sexual partners that men don't have. We need protection due to the child bearing. We live in a patriarchal society which marginalizes or contributions to society.
That said----we have each other. Women help each other. There is support to be had with issues like this. There are women's shelters and support groups. There are so many forums here. You are so not alone. There are so many to share your history and your struggle with.
There is no excuse for your husbands behavior. What he does is wrong wrong wrong. You have every right to be free of him and get a good life for yourself and your son. Join a church, join a support group, get some advice from a professional. Take control by becoming independent. It still is hard to cope with sadness and feelings of abandonment but taking action will help you distance yourself little by little and you will find your attention shifts to the positive ways you are moving forward and less to the past.
Bless your heart honey and keep posting