Expose the A immidiately to everyone. She doesn't deserve to treat your children or you this way and still get to live a Big Lie when people are in town. She deserves NONE of it unless she goes NC with OM.
And, if you are able to, expose the A in person or on the phone to everyone. It will mean alot more to the person you are talking to than sending a letter. Don't complain about her when exposing. Just state the facts, that you are worried about her, and this is not a good thing and they need to know what she's doing.
----"Et tu, Brute?"---- me:28 W:24 S4 T:6 M:4 EA Exposed: 5/21/10 Bomb: 6/20/10 (Father's Day) NC w/ OM: 7/10/10 W moved out 8/21/10 http://bit.ly/aOrZne - My sitch