Do I tell her I know, maybe it would take some of the excitment out of it? Show her that I am fine no matter what she does? Just when things were going well for me.
Just to be sure I understand, you went to her house to pick up the kids? So you were snooping on her tablet at her house? If that's the case then I think you were out of line and I wouldn't disclose anything you found on it to her because she is going to be VERY angry that you snooped. This kind of a thing always backfires on the LBS because the WAS then says something like "I can't believe you were invading my privacy like that, clearly I was correct in assuming I couldn't trust you, how will I ever be able to trust you when you behave like this???"
Basically ask yourself these two questions (from DR) before doing or saying anything:
1. What is my overall goal (save the M)? 2. Is what I am about to do/ say getting me closer to or farther from that goal?