Hi, Susan. You are making positive steps. How did the rubber band exercise go? I, too, think that is a great idea. I may do that myself. Practicing redirecting thoughts seems very useful...it helps me, anyway, when I discipline myself to do so.
As other posters suggest, you standing strong will help to show your DS that he cannot depend on manipulating you or seeking your sympathy to enable him in choosing a negative lifestyle; hopefully, it will be a push for him to work towards a safer and more positive life.
With that said, I humbly add that I am going through tough times with my teen and may have a long way to go till I am adept at detachment, etc., (!!!) but am trying to do what's best for him and us.
I have been following your posts but have not responded since I don't feel I have much constructive to offer but do send positive thoughts and hugs your way. Take care.