I completely understand what you are saying. My ex is a narcissist as well, who moved very quickly into a new relationship. He started living with her after a few months and not only won’t will he not give me his new address, but he no longer wants his kids to stay overnight as it might jeopardize his new relationship. It pains me when not only my children tell me all about his new life, but my friends tell me about their interactions with him on the street. It’s hard to remain calm and neutral. I don’t want to know, ever.