His calls initially were about how "the truth" did so much for him and how Satan warps everything outside of WTS
I can sort of relate to your story. There were two people whom I was really close to in my JW days. One of them is a guy who, like me, was raised a JW but didn't embrace the faith until later in his life. I embraced it in high school. He embraced it when he was 18/19 years old. He kind of saw me as a role model because at the time I was a model teenage JW and he was a frequent drug user who associated with gang members. When he finally got fed up of his lifestyle, he turned to JWism. It helped him leave behind what was a destitute lifestyle.
We became close, and I was even the best man at his wedding. He noticed that I began to have issues with the Watchtower, but he never confronted me about it. I think he really developed an appreciation for me as a person outside of the JW realm. When I moved away from my hometown and stopped going to meetings, he continued to check up on me and wouldn't press me too hard on JW issues. Nevertheless, I was familiar enough with the Watchtower rules to know that he could never truly be a friend to me unless I embraced JWism again. After a while, he got the hint and stopped calling me as much. I hear from him every few months now when we used to be in contact on almost a daily basis.
I'm pretty sure in his eyes I abandoned him as a friend because I stopped calling him and not the other way around. Unfortunately, I'm all too familiar with the JW rules and the JW mindset. He, like your friend, is way into JWism because he feels it has helped him out a great deal. In my friend's case, it helped him turn his life around. He's simply not at the point in his life where he's willing to reassess his faith. To try to maintain a friendship with him would simply prolong the inevitable. I preferred to cut ties with him right then and there before giving him the chance to ask personal questions about my beliefs that could potentially jeopardize my fade.
I have another story about the other friend, but I don't want to hijack your thread. Best of luck to you, man. I'm sure it'll all work out for the best in the end.