Update

[AJM]

GAG, it seems to me that you're looking at this in one direction when there may be several. Let me play it back:
1) XH is contacting you
2) XH may be scared and reaching to a familiar person he loved (loves?)
3) MLC often requires another crisis to change the polarity. Perhaps this is that crisis?
4) XH is making an effort to connect with you, but no way to know why
5) You don't trust his reasons (understandable)
6) You have your own life and things you do. He is not your responsibility
7) You still want to leave the door open. You obviously care about him enough to wish him well
8) You are not sure about the latest changes or if you want them.

The polarity, at least for now, has changed and you don't trust it.

That makes sense to me.

I think what you're doing is absolutely the best approach. You don't know if you can trust him. You don't know if you want to, but that is not a decision you need to make yet. You still need to figure out if you can trust him. That won't happen after one or two emails from "the dark side". (Postcards?)

I see no reason to act any differently or even think that this is anything other than him telling you information. I don't think your sister can know what he will do.

I think you can only take it as it comes and decide if you want to be there or not. If you want to respond or not. And I think you should feel comfortable with that because you are your own person with a life.

Just as you would with a neighbor....

Unless and until you need to make a different decision, the reality is that you received some emails that remind you of the old XH. Not really enough yet to think anything else I suspect.

Nice that you care and nice that you care enough to let him lean on somebody else vs. feeling like you have to fix or support him.

Be good to you and figure out what you want. Go from there, right?

AJ