Hello Maria:
Well, your son has not bottomed out yet. The question is, have you?
If you have, then get into Alanon or Naranon or both. You'll learn that addiction exists and flourishes in proximity to enablers. The bad news is that you have been that enabler. The good news is, you can learn how to detach with love to the point where you have huge influence (after all, you're his mom!). That guy is right - your son is in jail so there is hope. There is no hope for a dead man.
Hang in there. You've started the journey at the right place. You have your task before you.