Medication Abuse...

Posted in previous forum topics, I noted that my ADD partner has had addiction issues in the past; as well as, within the last year after being diagnosed with ADHD was found to be abusing his medication. Both medications that are to treat his ADD and his addiction were abused. After that came to surface, we spoke to his doctor and since March of this year, I have been dispensing his medication to him daily, I'd keep a few days worth in the house, and keep in touch with his doctor. Today, I was dispensing his medication only to notice that there were some pills missing, and others were cut in half. I can't even put my anger into words at this point. I immediately woke him up and questioned him about the missing medication, and suggested that it was of his best interest to be honest with me. He was, and told me that he did in fact commit the crime I'd suspected. Also, for the first time, I counted the amount of medication he had left for the month, and he is 3 days short; which obviously means this has happened more than once within the past 30 days. His behavior the past month or two has been all over the place, and I should of followed my instincts then. At this point, I am so angry, as he has broken my trust..again. His reasoning for taking more medication and being sneaky was because of the stress in our relationship. I'm always to blame for his lack of control. I walked away from him, as I do not have the energy to even talk to him about this because discussing it will get me know where. I feel like such a fool. I've enabled him by being in "control" of his medication, so now what? If he is still lacking control over his impulse/urges, why should I continue to babysit/monitor HIS problem? I have no idea what to do at this point.