Separation boundaries?

The last 6 mos have been especially rough in my marriage. We hit our lowest point and decided we were going to work on it...things were better for about a month, then we fell back to the old ways. We have reached crisis mode again. Many of our issues stem from core relationship values...communication, trust, etc. I know at this point our only hope to save the relationship is counceling, but he says its BS and wont help. I dont know if I can convince him to go. I plan to go by myself since I dont have anything to lose at this point. It seems separation is likely. Unless he tells me otherwise I still hold out hope he may come around. My concern is what happens during the separation...I'm thinking we should discuss some "ground rules" for that time. The biggest one for me is fidelity. (One of his buddies was recently separated and had a new partner within a couple weeks in retaliation. Now they are trying to work things out.) Seeing someone else while we are separated is a deal breaker for me. Are there other "ground rules" we should discuss? What is the best way to approach this discussion?