I am sorry you have to deal with those immature mothers at your daughter's school...that is so wrong! It takes a lot of effort to keep up the fake facade but I understand and still do it too. I don't know how old your daughter is but it is alright, and probably very healthy, to let her know that you are sad and why (only enough detail based on her age). I have tried to be open and honest with my sons as they grew up and asked questions when I was obviously struggling. It was difficult but being honest with them was much better than what they would have imagined if I kept silent and pretended everything was fine. I think it helped them to be more open with me about their problems as teenagers, which are horrible years for most, to maintain a healthy balance.