I agree with this, it more than likely started to suppress or replace something and then became an addiction.

I would also strongly advise you go to a doctor before trying to stop. If you have been a heavy drinker for a long time, you will have physical withdraw effects. Doctors can prescribe a short run of Diazepam which will help with the physical effects and also sedate your addiction a little. Don't take it for more than a week though, or it will become your new addiction.

I didn't take this advice and stopped overnight which could have been incredibly dangerous. I risked fits, seizures and all sorts.