I have the same problem, but haven't been at it so long. My husband's affair started at this time last year, and went until December, 2006. We went to Retrouvaille together, and the weekend there helped us very much. But the problem, as I see it is forgiveness. We have not fully made that step yet. There is a section of Divorce Busting that deals with forgiveness that explains well how a failure to forgive holds the person who doesn't forgive prisoner. And Michele's paper on this website about forgiveness is also good. But it's not an easy step. And the hard part is that we BOTH need to forgive each other. He still holds on to the petty resentments that sent him into OW's bed, and I hold on to the thought that he wanted to go there.
But as we get closer, and a happy father's day yesterday was a good step, I think of it less. I know that he can contact her whenever he wants, though he swears he has not since mid-December. It is time and patience, and working at forgiveness. If we don't forgive, then we can not trust. And if we don't trust, then we can't move forward. There's more work to be done here.
I agree. Avoid the medication, it doesn't solve the problem. If you and your husband can attend a Retrouvaille weekend (there are some international ones), it would be very beneficial. See http://www.retrouvaille.org. They understand because they are not counselors, they are other couples who have been through a broken marriage and have healed to become stronger than before.