What do you do?
1)Believe your own truth. If you instinct tells you he's using, he very likely is.
2)Make a plan to take care of yourself without worrying about him or his "needs".
You have needs too, and the right to live a life without addiction or an addict and to have a peaceful life.
It sounds to me like you've stood by him through thick and thin but he is still using.
That's his choice, but you also get to choose.
What kinds of decisions do you have to make, or are ready to consider at this time?