You need to be there for your daughter. Don't increase her anxiety. Show her that it is her choice and you will be on her side no matter what. Just as you are also on your sons' side! I hope you are encouraging him to do his best at school and head to college after...despite him 'going off the rails.' Show him that he can be whatever he wants to be, but it will take effort.
LHS I did not abandon faith and you don't have to either. But do more research on witness doctrine using outside info. The doubts you are having are showing you that they're wrong. It's not the way it should be.
Start letting go of this hanging on to appearances and witness social circles. It's all superficial. Start building other friendships.