I do think he sounds sincere, but as you said, he has also shown he is WEAK, and the recidivism rate for infidelity is very high unless you put a near-bulletproof no-contact/transparency plan in place.
Would he be willing to write her a no-contact letter, the copy of which would be approved by you, and it would be MAILED by you? (so that nothing is added/softened/etc.). Have you read up much on transparency plans? There is more than just changing his cellphone number, but that IS a very good start, as is the MCing. For a book, rather than "The Love Dare," I'd love to see you read "His Needs/Her Needs" or "After the Affair" together, and I also think you should see an MC who specializes in infidelity, because you're both going to have a lot of painful stuff to work through. But it CAN be done!
I'm so happy for you; this sounds like a great start!
