My situation is similar in that none of them know much about the situation, except one. He is a laywer (2 are actually) and I had confided in him some time ago since I wanted his legal advice in case things moved towards D.
I plan on telling them since it will be a hard subject to avoid. I think W is a little anxious about this. In some ways I would rather not talk about it much and just say 'we are having problems' 'W isn't sure she wants to stay in the M' 'W is sleeping in other room and we are separtated in house' and avoid the whole A topic altogether, but the one guy knows about this. I know what their reaction to everything will be. They will tell me she is having a PA, not just an EA, for sure (most guys focus on this point)!
ME/XW:47 S21, D19, S15, S14 M:21 T:26 W moved 6/10 I filed 7/10 D final 4/12 remarried 8/12 W wants to R 12/10 and 4/11 but I decline
