Trying to help Fiance's addict son?

First off Im so sorry. Ive been there. I was a meth addict for a long time, like 17+yrs. The way I got clean was, I seen the way the drug changed the way I think. Like, people I liked while sober I hated while high. Unfortunately I had to go to prison 3 times for a total of 7 years to see this. Meth is the devils drug, we all know that. Rehab most likely wont work unless he wants to change. Now you need to make him want to change. Doing that isn't going to be easy, and it will take everyone involved in his life to get involved. Watch a few episodes of A&E Intervention for tips and pointers. Get in contact with an interventionist to help you. There is only two things that will happen if you all don't get involved. He will go to prison where he will have to fight and or **** every day...... or he will die. I lost my only sibling to a drug OD on top of it. And even after he gets clean, it wont be easy to stay clean. This will be a struggle every day for him for many years. Best of luck.