You have gotten some sage advice here. What good would it do to tell him that you know he married his affair partner? I would just go on about my business and allow them their "wedded bliss" for however long it will last. Now that it is out in the open, it's not going to be all that exciting because the cat is out of the bag and no one is reacting to the secret the way that they had hoped. The less you give him in the way of a reaction, the better.
BTW, my xh married his affair partner too...but the "wedded bliss" and people didn't react the way he wanted and it was right back to business as usual, i.e., working, paying bills, etc.
Don't bring yourself down to his level. Continue as you have been.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
