It sounds like it could be, if it is, Remember this is all about her there is not one thing you can do to speed this up or snap her out and make her see the light.
Looking at this as a temporary mental illness will help. You must make a choice though. this will be the hardest thing you have ever went through. Can you forgive her, it's pretty much an all or nothing type of a deal.
You must know this is a long journey. You may do everything right and still might not be able to save your marriage. I'm not trying to be negative just real.
No matter what you say or do you will be her #1 enemy. You must have patience like never before x 1000000.
Stay out of her way and focus on yourself and children. This will transform you into a much improved you (and hopefully your wife as well) She is on a journey and your not invited. While she is in outerspace, your kids need you like no other.
Don't ever confront the OM, he is a low life user. If your wife is in MLC she is not capable of having a real R with anyone. This is a life ring to someone who is in a panic and can't see she has a Ship in you.
You must let her go a distance your self from the drama. She will test you and she knows exactly what buttons to push.
MlC'ers thrive on negative emotions. SHOW HER NOTHING BUT HAPPINESS. It will drive her nuts and make her angry but don't fall into her traps. IT ONLY FEEDS HER JUSTIFICATION TO ACT THIS WAY. Deep down she knows something is wrong. Denial is huge in this.
