Tell her that she is DONE talking to him if she wants to stay with you. Cancel her phone, shut off the internet connection, whatever it takes. But most of all, expose (or re-expose) the affair to everyone you can, and speak to your daughter about why what mommy is doing is wrong, and that it is WW who is tearing your family apart, not you. And then be strong.

Your situation is not going to change until you change what you will put up with.
Worth repeating.

Look, the ONLY people who get their spouse back are the people who quit being afraid. They start being MAD. How dare she do this to you and your child?!

She has to respect you before she will ever want you. She has nothing to respect right now, because you are being a doormat.