Not to be picky, but "telling" makes YOU sound like a RAT and that's NOT what's happening.
Expose.. WELL... to anyone who you think may put pressure on your partner to end their affair.
Don't just expose that they are cheating.. Get the key points in :
1. Infidelity is addictive and destructive - it has no long term hope 2. Infidelity is hurting me and our family 3. I would like you to support our MARRIAGE and exclude WS and OP from any interaction from you until they stop carrying on this way 4. I want my marriage saved and will not lower myself to their level - please support my marriage and stay out of the mess they are creating for themselves
