It is a load of cr@p. But, remember, your W probably truly believes this. In fact, there are many people that believe this. The best person to talk to your daughter would be a pastor or priest and yourself. Try not to get angry. Just give your daughter the facts. If you haven't told of the affair to them yet, it looks like you are going to have to. I would also make sure to not "blame" your wife or your D will just think you don't like her (your w) and that is why you are saying those things. Something along the lines of "When someone is in an affair they think and say things that they would not normally say....,", "I love your mother, but she made a choice to have an affair instead of working on the marriage," etc.
This is your daughter's mother, who your daughter loves very much and always will. Talk about the choices your wife made, what's happened because of it, and what COULD have been done. You won't stop your daughter from loving/supporting her mother, but you can hopefully allow her to see the truth of the situation.
