If your marriage broke up, would you tell your children the truth if one or the other had an affair? Do you think it was right for them not to tell Jessica and let her believe it was Daff's fault and not Richards?
I think it depends on the age of the children. In this case I think Jess is old enough to understand on some level. Maybe not all the details but a sugar coated version. It breaks my heart a little that she hates Daff and thinks it is all her fault when in reality it is all Richard. If the kids were younger I don't think they should know. Maybe just tell them something as to why Mom and Dad don't live together but remain amicable kwim? No fighting or bad mouthing the other in front of the children.
I think at any age children can know that people fall out of love but can still be friends....I don't know that children need to know the truth of unfaithfullness or greed, addictions, untill both parents can tell them without hate. IF they never get to that point get a third party to help. I knew what my dad was doing and it was his fault but part of me always wondered what made him cheat on my mom, what was her issue that sent him to do it?
I think, in this situation, that the girl needs to know. It's had a huge affect on her relationship with her mother, and while I'd hate to have it affect the one with her father, the truth needs shared so healing can begin. She can't heal her relationship with her mother as long as she isn't being told everything, and she's old enough to know.