Hi merrygoround. My situation sounds similar to yours. We must draw reasonable boundaries based on behavior.
My boundary is: I will not allow active addicts or people involved in illegal behavior around my son. I will not allow people who are on drugs or I suspect are on drugs in my home or around me or my family. If you are involved in any of these activities I will not answer the phone when you call. I will not answer the door if you show up. If you refuse to leave, I will call the police and report that you are on drugs and harrassing me.
I don't answer the phone when he calls and I only return calls after 2 messages and 24 hours. This seems to put an end to most contact attempts when he was using.
Now he's not using and it's a whole other ball game. It's even more worrisome now that he's clean because he STILL isn't a good example for his little boy. PM me if you want. I can give you more details.