I really can sympathize with you! I don't have pre- e but I do have GD and have kept it a complete secret.
i am curious..why are you keeping it a secret?
I have found that people have been very understanding. Most sympathize about how it stinks with all of the holiday goodies that are around. I teach and my Kindergartners know that I have to test my blood (I have to set alarms during the day to remember). As a result of their kids sharing at home, I have had three moms contact me to share their GD experiences, tips and tricks. My teammates even made sure to have some low carb options at our holiday party. I guess my experience has been that, at least with GD, people have been very kind about it.