I guess it all depends on the relationship you have with your spouse and the kids. In my situation, my W and I have even to this day, never argued or yelled at each other. We are very civil and even friendly so the kids have never seen any problems between mommy and daddy. We have been living apart for almost a year. My kids do every now and then ask questions. My 5 asked me the other day if mommy was my friend. My 3 will always refer to mommydaddy house instead of mommy's house or daddy's house.
It was just our decision to not say anything at this point. My thinking in the beginning was if we reconciled there was really no need to have the kids know. Of course, we were able to transition the kids into our separation since it began in the summer and the kids would go between grandparents, so it was kind of like a fun vacation for them.
Just do what you feel is right with your kids. Do that and you cant go wrong
Me: 42 W: 32 Married 7 years together 8.5 S1: 7 S2:7 Bomb #1: 09-16-13 Recon #1: 11/13 A discovered 04-03-2014 W filed D 05-19-14 but never served me I filed D 12-02-2014 S 05-31-14 Divorced 5-19-16