First of all, welcome to the forum. Talking with him about this may help, but as you know. Unless he really wants it, he won't get clean. You can't make him do this.
"When your desire to get clean, is stronger than your desire to use. Then, you will get clean" GTMI
Unfortunately GTMI is right. Unless he wants it for himself, you can't do a darn thing. BUT, you can stay sober for yourself, and hopefully he'll see what you have and want that for him. Try to learn from your own relapse and identify the warning signs that led to using.; Next time those things start to happen, you'll be able to reach out to others before going to the pill. I'd definitely make sure your monies are separated from now on. Double up on whatever you're doing for your recovery. Keep posting here and welcome!