Just get to the ten year mark, because of the financial benefits. Work on getting your finances and the house optimized so that if you get divorced then, you're in better shape. Find something new to focus on - when my H had his affair, I decided to train to climb Mount WHitney. When we divorced years later (after an initially successful reconciliation) I took up playing the drums in a rock band. Both times, I found it very helpful to have something challenging to focus on that had nothing to do with the relationship.
Be mysterious! Go out and don't let him know what you are doing (even though it's completely innocent). Let him wonder about you - trust me, he will. And even though he's having this flagrant affair, it's going to drive him crazy to think you might be out there enjoying the attention of other men.
Just dress up hot, splash on a lot of perfume, and tell him you're going out dancing one night with one of your single female friends.
