If you are female, contact the nearest battered women's shelter. They can give you advice, and maybe even assistance.
If you are male, unfortunately there are no battered men's shelters. So the best advice would come from talking with a therapist (whose job it would be to help you know that you are seeing things clearly, and to help you decide how to best-handle the situation). Regardless of whether or not you are religious, Catholic Social Services offers non-religious, psychological counselling that is charged on a "sliding scale" (meaning the less you earn, the less you pay) .. which may or may not make it affordable, depending on your income.
When it comes to abuse, understand that we should never try to stay in an abusive relationship. We cannot make others change, and so we need to get out before the situation escalates.