still separated, headed for D?

[WhatNow]

As you know, I too am walking the tightrope of staying detached and not allowing cake-eating but still letting him know I am not ok with the current sitch.

I think your quote above on detaching tells HOW to detach. I think you are more along than you think. You want an outcome, but emotionally you know you will be ok either way. That is a big step.
It doesn't seem as if you are manipulating him. You are controlling your behavior to fit your boundary line. You are trying to not allow him to cake-eat. I don't think discussing family facts would be cake-eating but that is for you to decide. If it turns to discussing feelings about the facts, that may be. He's the neighbor, remember!?!? lol