welcome to sr, sorry that you are in so much pain, there are a lot of wise and caring people here who want to walk through all of this with you. maybe you can start by reading the stickies at the top of the forum page. here we recommend the book "co dependant no more". its a good read. keep posting as much as you want. the addict in my life is my hubby. your so right there is nothing you can do to help your son, he has to want to do that for himself. maybe its time for you to take a step back and allow him to suffer the consequences of his actions, maybe he'll have to hit a bottom before he see the need to get serious about his recovery.
maybe its time for you to take the focus off him and turn it onto yourself. do whatever you need to do to make yourself feel better. maybe start a project or something, anything you can do for now to keep your mind occupied. its hard to do i know and i do understand. when i first came here i thought i was crazy, but they told me to do what i'm suggesting to you.
we also recommend alanon and naranon meetings, they help so much. i'm so sorry and i pray that your son will find his way soon. keeping all of you in my prayers.