I understand what you are going through as I have been living the same thing as you are now for 2.5 years.
The only way to get over this person is to have absolutley no contact.
I can't tell you how much better I feel now after not speaking to OM for so long. I have gone from utter despair and depression (not being able to get out of bed to look after the kids type depression) to feeling like my old self again. If he was still on the horizon, if I could contact him or see him, it wouldn't have been like that.
My marriage was far from perfect - I had an emotionally abusive DH which didn't help keep me from dreaming of my OM. But having the 'affair' didn't help. It just made it worse. It confused me, made me pine, feel trapped, sapped my energy.
Anyway, I told my DH and we went through hell and back. By then I had decided if I was going to leave DH I'd do it without running to another man. That made things easier - helped me break down each part of my life more effectively. He convinced me to give him another chance and he went to councelling to sort his head out. It worked, he took responsibility for his part and I did mine. Now we're so much better together.
We'll never have an ideal marriage, but we do have a lot and now I count my blessings for my DH and my family everyday.
My life is better without the complications and emotioanl trauma of an affair and yours will be as well so try and put it behind you. Work hard, start something new. Your efforts may seem fruitless at the start, but stick with it and you will find you will move on.
We are all vulnerable to temptation - even the people who believe they are not. If you find yourself in the thick of it, just keep the faith and get out as soon as you can. Look to how you were before it all started and aim to get back to being that person again as soon as possible.
You'll get your down days like I do. But they are infrequent now and I just chide myself for being in a whimsical kind of mood when they happen and I start dreaming of him again. It's usually around mid cycle - ovulation time - so I can tell when I'm going to feel at my weakest.
Good luck - to you and all of the other MNers on this thread in the same situation.