I understand how this is very heart-wrenching for you. After reading DB, there is a section about infidelity and you have to "stop think" or something like that, where when you're having bad thoughts about it, you have to consciously tell yourself to stop and enjoy yourself at the moment!!!
If you want to reconcile and can see yourself forgiving your H, then give it the best you can and do some MC once you are both ready.
Also, remember affairs are a fantasy world that people escape to instead of dealing with their real life problems. He did not really love this person, he just thought he did, because he felt like he was missing something in his own life.
Things will get better and I wish you the best. Keep your head up girl!!!
M: 27 H: 28 T: 8 yrs M: 6 yrs Sep: 2/18/12 (I have no feelings for you!) EA/PA Uncovered: 2/26/12 H introduces OW to his fam: June H moves ALL stuff out: July