Hi...
I'm so sorry you are going through such a painfull situation...
I just wanted to help you think about something. When you say "I don’t think him leaving is the best thing for us", you are considering there is a common feeling of "us", that is shared by you and your husband. But maybe there is no "us". There is a "me", and a "you", and the us that used to be is no longer there. If there is some kind of "us" there, it will not be the time he spends away that will end that, on the contrary. But if he has moved on beyond that "us" you once shared you should prepare you heart to handle the grief. No one dies of it, you know? It hurts like hell, but we can go on with our lives, one day at a time. It's better to live a real life than a fake one, even if it hurts so much. There is life beyond the pain, and it will be an honest, real life, instead of a fake one. No one deserves to live a fake happiness.