I am by no means experienced in that arena - just know what I've read here - mostly from Mr. Puppy. But I think the answer must be no - you don't tell her how you know - just THAT you know. And then Puppy has a line that he throws out for the sh!tstorm that may follow (blaming you for snooping, denial, etc.) "W, we both know the truth and it is insulting to me and to yourself for you to carry on otherwise." Or something like that
And I'm thinking have that convo at home - and stay put. Don't leave. Keep the phone and your car keys/house keys on ya.
If your boys are home - which I'm thinking I would try to farm them out (movie, bowling, friends' house) but if they are home, if she erupts, cool headed Soldier Dad says "I'm going to keep my voice at a lower volume and be careful of what I say b/c I know our sons will never forget what they overhear today. " This will highlight her ranting. She'll either stop or carry on. That is up to here. You will be all poise and class.
Greek
Me45 H46 T25 M22 S21 & 19 D13 Separated and filed 8/08 Moved home 11/08