Dear Jadeblossom,
I am hearing myself in your words... I came to this board for the EXACT same reason - looking for some help to get over a married man.
I posted my story on one of the "having an affair with a married man" threads (I do not want to take up bandwidth here again, but you can find it by clicking on the link that shows all of my posts, if you are interested). I am not having an affair, I don't think you could call it an affair - it was only one night (in March) after 10 years of friendship (albeit, some of those years were very passive - not much contact between us).
I miss him, I want him, I search for him everywhere... it is harder than I could have imagined... but keeping yourself busy is a very good idea. Noddy also gave me some good advice about shaping my own perceptions of the whole thing (just making it a sweet memory that I can return to, but not try to repeat, etc.).
I find that the more I talk about him and the more often I speak of how I feel about him - the more it hurts. So, in the beginning of this message I was tempted to write about why and how I fell for him, but had to pull myself back and be more rational - and it really helps.
Also, the whole "sleeping with other men" idea should not be dismissed entirely.
I do not suggest that you run around and sleep with every upright animal who has 5 appendages, but I have found that relieving some of your physical needs and fulfilling some desires is very helpful too.
If I figure out anything else that helps, I will definitely post here...
Good luck to both of us!