If she doesn't know that you know about the A, then maybe confront her with that knowledge first, then tell her that you will not live in a 3 person Marriage, and until she has NC with the OM, this is what you are doing.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized
