Hello,
I didn't read anything other than the OP but let me give my difficult child point of view on that.
The thing that most stands out to me was the quote of "My son is an addict I cant change that, I guess I feel like I have to be able to change something I have been powerless for years in his addiction."
In order for your difficult child to wake up, and this is coming from a formerly active addict in the same position, something needs to happen. It may even take a few things.
I'm not sure what your state is, or what it offers, but here in Florida there are options like the Marchman Act to place someone of age in a rehabilitation facility against their will. This may be something that could change his life, and a lot of the work may be just him having a sober period to see things from a more clear point of view, along with the treatment and the idea that people are not going to let him get away with that lifestyle. By letting him live with you, although it may be more comfortable for you, you enable him to easily live that lifestyle with comfort, which doesn't redirect him in the slightest - at least from my experience.
When it becomes harder for someone to maintain a lifestyle of active addiction, and the lifestyle becomes more miserable, is when one starts to rethink it - and when that happens, it's good if they are rethinking it with a sober mind.
A long-term rehabilitation may be a good idea. Take a look into it if you haven't already.
I'm sorry if any of this has already been posted, thought of, or even tried as I realize I don't have the complete background on the situation.
Best of luck to you,
Alex
