One of my Welcome to Oz community support groups is WTOChristian. Often, members feel conflicted about divorcing an abusive spouse because of what the Bible says.
Here is what the book Keeping the Faith: Guidance from Christian Women Facing Abuse by Marie M. Fortune (1987, HarperCollins) says about the subject:
We have always taught within the Christian tradition that the marriage covenant is broken by adultery or sexual unfaithfulness in marriage. The main reason that adultery is a problem is that it results in broken trust between man and wife. If the promise is made to be monogamous, then adultery breaks that promise.
But we should realize that there are other kinds of unfaithfulness. Bringing violence into one's marriage is also unfaithfulness. Once violence has entered a relationship, trust is destroyed. If you can't trust your [spouse] not to hit you, what can you trust?
[Anyone] who brings violence and abuse into [his or her] family life is putting asunder the marriage covenant that God has blessed. The violence is what breaks up the marriage, and the one responsible for that violence is the one responsible for the breakup. The actual divorce is in fact only the public acknowledgement of the private truth that the marriage has long been since destroyed by abuse. You are taking steps to let other people know what has happened to remove yourself from a destructive situation and get on with your life.