Have you tried counseling? Look into Cognitive Behavioral Therapy. Sounds like you need to talk to someone to work through your emotions and redirect your thought processes. Beyond changing your environment, which will immediately make things easier if you're engaging in alcohol/drug consumption mainly around others, that's probably the long term solution, if not antidepressants.
Go to the library or pick up a used copy of "Mind Over Mood".
Don't buy into bullshyt like wheat consumption is causing your drinking and depression.
Your depression is being fueled by your drinking. It took me a long time to realize what people meant by alcohol is a depressant.
At the end of the day, if you're not physically, but mentally addicted to alcohol/drugs, you can stop through sheer willpower or with the help of a professional by changing your environment and improving your moods that lead to addictive behaviors by redirecting your thoughts.