Pink - my W had a 6 month affair over a year go... i still have a hard time every day with it. The one thing i would suggest is you be 100% open and honest with him, my W has not to this day answered any of my questions about the actual A and i can only say it is a HUGE road block in our current situation.
we have kids, but if we did not, i hate to say i would also have seeked divorce. he probably loves you but can't deal with what you did to him and is most likely why he has not pulled the trigger on the D.
think the book i wanted my W to read was "not just friends" might help you in your situation.
Gman
M-37 W-36 S-11, S-9, D-4 PA exposed 3/13/10 10/19/10 moving on... most up to date sit