LWB,
Ediemarie makes a very good point about where you are in the relationship. I'd also add that you need to consider the tension level in the household, and how well you are able to DB under the conditions. For example, if the coming and going upsets and angers you DBing might be more difficult. So having him spend more time at his father's house may be better. I know for me, there was a huge amount of tension in my house just before the separation. Also, we both seemed to have difficulty with the other staying out late. That was my first time actually "going out" and staying out late (sometimes just forcing myself to stay out late to prove I could do the same thing). It was kind of interesting how my husband had a difficult time with me doing something he had often done throughout the marriage. He would go out with buddies from work or other friends. But when I finally did the same (because he was leaving) he had a difficult time with this. I think it was because I never hung out with girlfriends at night, or stayed out late before (other than PTA or other "married women" stuff). Heck, before all this happened I had never been in a bar before!!!! So I made some huge 180s!

If I were you, I would take advantage of the times he is there by going out and doing other things. If he stays at your house, you go out and stay out late. If he asks where you went say, "Oh, just out with friends...." and leave it at that. Even if all you did was go out to Barnes and Nobles by yourself or hang out at a coffee shop with a good book!

By the way, all space is good for him regardless of where he goes. Even if it's with OW. "Losing" his family and the daily contact will become excruciating. Some of things I did was pack up things my husband might need. In addition I put lots of photos of the kids, and him with the kids. Also, I snuck in a framed wedding photo too!

Keep in mind, when he's gone you can do lots of great family things with the kids. Things that he won't be part of because of the separation. Take lots of photos, put them up around the house, give him one to keep at dad's house. He will miss not being part of these fun family events.

There is no arriving, ever. It is all a continual becoming.