There is a reason why benzos won't be prescribed to active alcoholics and that's because you can literally die if you mix them. I would be completely honest with your docs about your past drinking situation.
Otherwise that is another common problem is that docs sometimes will prescribe a benzo for a sleep aid, which is a good way to get hooked on them, especially xanax which is pretty much the most "hardcore" benzo around.
I would start seeing a therapist for your insomnia and anxiety issues, as well as for help with your alcohol recovery. There are tons of medications on the market that are non addictive you can be prescribed if needed.