If you think you have an alcohol or drug addiction problem, you must seek help. Your Board of Nursing, as other professional boards everywhere, knows that nurses can be suffering from problems with drugs or alcohol, and stand ready to work with you in your quest for help. This is not to say that they are lenient or offer any services in this regard to nurses, but they will work with a nurse who decides to seek help.
The worst thing you can do is go to work impaired. You could make an error that impacts upon a patient, which is dangerous for the patient, and dangerous for you.
In many states, nurses may self report their problem to their State Board of Nursing who will refer her to a third party agency best suited for your particular state and/or problem. It is advisable to self-report before an employer or co-worker reports that you are working impaired.