Don't believe for a minute she's ended anything. This was just the first step. Now get legal stuff going, make sure she knows it.
Keep the pressure on.
Realize she IS going to keep throwing tantrums until OM is OUT of her system. It will take at LEAST THREE MONTHS of no contact between them before you begin to see her normal again.
Her hormones are all out of balance from infidelity.. Keep the pressure on so she knows you aren't kidding. She IS going to try to play you and keep it a secret.
I did that to my husband for god knows how long, until I finally took his asserting his rights seriously.
THIS is the TIME to make sure she knows you mean it. If you issue this to her last night and do NOTHING today she will not take anything you say seriously after that.
you have to show her you are serious until she follows through and ends her behavior.
