When someone you love is an addict

I've been an alcoholic and had other addictions, and people I've cared about have had addictions as well. I think I should say some things about what you can do if a loved one is an addict.
First of all, no one can make anyone change.  The person has to decide they want things to be different.  Don't blame yourself for not being able to convince them to quit. 
Don't make excuses for them and don't believe excuses.  Don't bargain or make threats.  Just tell them you don't like how things are, and if things don't change, you won't be in the addicts life any more.
Addicts don't quit until they have no other choices.  The more you protect them from the consequences, the longer they will be using their drug of choice.
Don't loan them money, pay their bills, or anything that gives them freed up cash to buy their drug of choice.  That drags out the recovery process.
There is help out there, AlAnon and co-dependents Anonymous are good places to start.
You aren't alone in this, don't feel that you are.
 
http://www.thecounselingcenter.org/The_Counseling_Center/10Ways.html
http://health.howstuffworks.com/mental-health/10-ways-to-cope-with-addict-in-the-family.htm
http://www.psychologytoday.com/blog/almost-addicted/201312/five-must-do-things-if-family-member-is-abusing-drugs
http://www.health.harvard.edu/healthbeat/when-a-loved-one-has-an-addiction