Bbj, have you thought that maybe, just maybe, and forget I said it if you think it is stupid, that you are ruining any chances your S6 has to grow up in a family. Once these frictions continue and the "bad respectless relationship" becomes a "standard" and Dan feels he can get away with anything, there is no way you can pull this together again.
You are losing your bargaining power right now. You allow him to detach emotionally completely, you are giving him a head start, he will be so fed up by the time he leaves he will not want to look back... All he will be thinking of is walking on eggshels with you, you complaining, being emotional, fighting etc etc...
Forgive me I am harsh, I am just trying to help. As always, you can ignore me. K