Hi pmc,
My W decided to have a PA earlier in the year with an on going EA (who btw also lives only a mile away) after she decided she felt trapped by our M and was looking for a way out.

Such an event awakens your emotions to a very conscientious level we have not experienced in a while. At first most are a result of the pain and hurt, hence your anger. Search down deep inside and ask yourself do you really want to live the rest of your life with this woman. If the answer is yes, than in order to heal and overcome the anger, you work on forgiving, but rather focusing on showing her that you forgive, focus on demonstrating to yourself within that you have forgiven for what had happen. This is the first step at healing the hurt and allowing your emotions about the A to stay in the past. At first you will need to conscientiously give yourself the gift of forgiveness for your sake at a very heighten level of awareness daily in order to overpower the anger. Eventually, as you allow your forgiveness replace the anger, you can gather more strength from how it makes you feel as a better person and it will cease to become a struggle to be with your W.

As far as your anger towards OM is concern is allowing him to hold a power over you as to how you will live the rest of your life!! You need to let it go. He is undeserving to have such a hold on your emotions and by letting the anger go, you regain control of yourself rather that relinquishing it to him. Prove to yourself who really is the better man and then bury him (figuratively speaking of course) and forget him. Don't let him get in the way of what you want in the remainder of you life. In time you can succeed.