Yes the way we handle these situations is CRUCIAL for how kids will cope with it. I would encourage you to talk to whoever told your D that her mom is a liar. Never let the kids know what is really going on because unless they are in danger they need both parents in their lives and you CAN make that work.
As to their hope of being a family..that likely will change over time...depending on how well THEIR interests are being made a priority by both parents (and their families and friends). A lot of kids are able to recognize that mommy and daddy are awesome people but they shouldn't be together. Even at a young age kids are more perceptive than we often give them credit for BUT of course they blame themselves early on.
