krhea,
Sorry to hear your week-end didn't go so well. There are ups and downs. That doesn't mean the next visit won't be good. Stay strong and stick to your boundries.
Your son is young, he has a lot to learn. On top of him having an addiction he is also being a teen. We know that teens are unpredictable even without drugs. Maybe you can't blame all of his behavior on drugs.
Hugs...............Lo