"I know this sounds awful but I'm not even married a year. It just feels so much like a huge failure"
This is another form of the sunken costs fallacy and it basically causes people to keep on making poor relationship decisions.
There are two ways to understand this process, both involving avoidance. One is an avoidance of disappointment or loss when something doesn’t work out. When a relationship doesn’t succeed, especially after a long period, especially after many shared experiences and especially after developing a hope that the relationship would be a good one, it is a loss. It is a loss of what might have been and an acknowledgement that a part of one’s life has been devoted to this endeavour. He was though never your project to rescue and or save.
Another angle to evaluate is that focus on “sunk cost” creates a distraction from one’s inner truth. The sentence often goes like, “I’ve already invested to much, so I can’t notice my thoughts and feelings that are telling me to end or change this relationship.”
This is a type of insidious defense against noticing yourself. You enter into a neglectful relationship with yourself which divorces you from your inner thoughts and the quiet feelings that might guide you in your life. In other words, thinking about what already has been may prevent you from deciding what you want your life to be.
You can and should start divorce proceedings against him when you have been married a year. Being in a relationship with him regardless was never going to work because he is at heart a violent drunkard who fooled you with nice words. Your son has also suffered as a result of your poor choice in a man.
And look at you a lot closer as well; why is your relationship bar so low that you allowed this man into your lives in the first place?.