LIKE I SAID INITIALLY WHAT HAVE I DONE? I AM AFRAID I MOVED THINGS TO FAST BUT NOW WHAT DO I DO????!!!
You did not have an affair. You did not make the first of several moves to put your marriage at risk. Your WW did. You did not make a conscious choice to be unfaithful. He moved too fast and in the wrong direction. By telling the OW to leave your WW alone is moving things too fast? I am curious why you see it that way?
If your WW husband truly was remorseful he would be asking himself WHAT HAVE I DONE? This is his to own.
You were simply responding to his actions that cut you to the core. Do not take the blame for this. DO NOT. So what you said something on FB. If he wouldn't have cheated you wouldn't have had it to vent about. Every action has a reaction.
You are hurt and scared, understandably so. But do not accept responsibility for the affair...ever.
Again, your WH laughing at your response is not a good sign. IMO, he is dismissing your feelings, your hurt and his actions. He is manipulating you and the situation.
Get mad, fight for yourself, your pride and your dignity.
Keep your head up. You are doing fine.