i agree with the others, his pill intake is his responsibility. unless he seeks help, his addiction will get progressively worse and you hiding his pills will not make him be responsible for his own actions. i think you did the best thing for you and for him by allowing him to be responsible for his own bad choices. when hes bent on using, there is nothing you can do to stop him so maybe not it time for you to focus more on you.
have you attended any alanon or naranon meetings? keep reading and posting. you and your family are in my prayers.