I for one - think you did very well - magnificent even. You set the boundaries for your H. You reminded him of the reality that this is D and that he needs time with his S. You held your own and you appeared to do it with style and a sense of calmness about you. You did well.
Regarding S and his location. You have every right to know where your S is staying and with who. Again- you did well to establish this boundary.
Regarind H living with OW. I tend to agree with Sherman on this one. I think my own sitch would move faster - and I mean W would start having problems with OM - if she jumped right in. The only reason she isn't is because she thinks she is not doing anything wrong right now and doesn't want anyone to know about OM - she is embarrassed (I would be embarrassed to be with this OM too ). She wants her family to think that she didn't start anything with him until after our D was final. So for you, the fact that your D is final and a week later moves in - reality will smack him upside the head like a giant rock! Believe it. It is going to happen. It is just a matter of when.
Continue to detach from it as much as you can. You have to take care of your S and you are doing a great job of this. Your S is lucky to have a mom like you in his life. One that cares so much for him - someday he will thank you so much for what you did for him now.