The best idea is to call a DV hotline - this is a confidential call. They will guide you in how to get out - they can also refer you to shelters where you and your son can stay in the interim. These shelters look like any other home, they are kept in secret and your A will NOT be able to find you or your son.
You have to put thoughts of what could possibly happen regarding a divorce and custody out of your mind. These thoughts often keep spouses in unhealthy and dangerous relationships. This is a dangerous relationship for your son as well. You cannot control the A while you are there. Please don't wait. Bad things happen when people wait.
I live in the Deep South too - not all are backwards, not all are accepting of alcoholism and Domestic Violence. I don't know one person who is accepting of domestic violence.
Peace and hugs.