Welcome Blue. The first thing I would say is definitely check out the friends and family of substance abusers
forum. You'll find a ton of useful info and advice there directly relating to your situation.
Something I've noticed about addiction in personal relationships is that there is a natural disconnect between addicts and non-addicts who try to help in that the addict may view the non-addict as someone who just doesn't understand what he or she is going through. This may be the cause of some of the distance you feel.
Also, keep in mind there is nothing you can do to make him get better; he has to ultimately initiate that process himself. Just my two cents.