Maybe your energy is still being sapped because you give so much of it to your M and W. I'm not sure why you call her STBX as you don't seem headed for D.
I don't think this holding pattern you are in is benefiting anyone but your W, who gets to feel good because you two are such good buddies. But, you aren't. You aren't friends. You aren't lovers. You aren't partners. It hurts you when you spend time with her. It hurts you to keep up this pretense. It hurts you to stay in limbo. It hurts you to keep doing things for appearances, to feel like you are the evolved separated spouse. You aren't evolved. You are stuck in a cycle of slow self-abuse. It is exhausting. It is bad for your immune system. It is bad for you.