Am I stalking my ex boyfriend by calling or texting him 2x a week?

I don't believe that you're stalking him, it's natural to want closure at the end of a relationship, especially when issues haven't been resolved. However, he's making it apparent that he isn't up for any kind of communication at the moment, so maybe you should let it go. Sometimes people push away people who truly care about them, this could have a lot to do with the addiction that he is going through. He may eventually come around when he deals with his problems and realizes how he has treated you, but for now you should do what he has asked and try to move on. Good luck.