Just my perspective here, which tends to run a bit cynical, but here is what I see in what you wrote, and based on my own experiences with this sort of thing to date...
1. The reason he sounds confused is NOT so much because he is actually confused, but because he is planning 2 different lives at the same time.
A) There are the things he thinks he is going to do with OW and the next 30 or so years of his life. When he moved out, he made the FINAL decision (in his head) that this is what he was going to do. He already went through tons of thought and DECIDED that he will change his life to OW. But in reality, as he found out, you can't just decide this, nothing is final, nothing is so simple. (He found out that he still loves his family and his house and his business/money. She loves her children in another city. And so on.) And they are not established yet, so he can't live/say/do them yet. They may never establish. But right now he STILL thinks he is going to do that other life, and working on it. (it has nothing to do with you, you can't do anything about it, THAT is the selfish MLC/depression/obsession/whatever his problem is in his head speaking).
B) There is also the life he had with you (and everything still associated with it like house, kids, business). He thinks he will move on from those things, or change the way he deals with them in his new life, but since the new life is not all worked out yet (and may never be), he is hanging onto the old life too. And he sincerely misses some of that too, and has found that he doesn't want to let it all go. But he made such a mess of his/your life that he doesn't know how to fix any of it either, and how can you forgive him, and what will his friends and family think of him if he doesn't follow through now, and so on.
A and B CONFLICT!!! He has to keep saying one thing to OW, another to you, and hope that his life will find it's way to happiness for HIM. It is extremely selfish and irresponsible but he does not see that or he no longer cares (for whatever reasons, his internal problems). Not confusion, but irrational to us, nonetheless. Does that make sense?
2. Re: email about D - be careful. The courts look very poorly on interference with visitation with children. IF (and just IF) you go to divorce, then many financial and visitation things will have to be worked out. You don't want to look bad in front of the lawyers and/or judges as having been the bad guy about letting D see her Dad. I know you're not, but it could be seen that way if he keeps documenting like that in emails. I know it may never even come to that... but I can see it Mila, so it's there. My advice, yes actual advice today, is that you establish visitation for D and your WH for now. For example, every other weekend and one night a week. Or whatever you agree to. I know it applies more to kids under 16 then over, but it will protect YOU. If WH is out of town, you have the option to acquiese and offer him different times in exchange. Or to say, hey buddy, you missed your date with D, that is too bad! My 2 cents.
