Breec, I just have one question. You are writing all cocky and sure of yourself (which is not a bad thing believe me), but I am wondering if you can maintain this when you do get home? When he confronts you with not answering his calls can you calmly tell him "that you were working".
Remember, this is not a "tit for tat" thing you are playing, this is for your recovery, for you to feel good about yourself and not allow yourself to be manipulated by him, but by setting this boundary, are you willing to stick with it?
It is good that you feel good about this please don't read this wrong, but to me this reads as if you are trying to teach him a lesson and playing a game, sort of like winning the battle for today, but not doing what you need to do for you. I don't know, perhaps I am reading this all wrong.
By the way, I also train dogs part time and believe me when I tell you, the area the dog will explore gets bigger by "miles" the bigger they get and if the dog is not given boundaries and leadership now at this age, he will be uncontrollable in 6 months to a year. Get a new obedience book, the one you are using is garbage. You can private message me about the dog if you want.