I talk in my sleep, so she'll find out one way or another.
I tell her exactly what my commute is like, even the minor run-ins that don't result in me taking a bail or getting bumped. She freaks out sometimes, but she also doesn't try to stop me, except for this past Tuesday.
That was the first day after all the Seattle snowfall, the roads were cr@p, people were still trying to drive and sliding all around... she convinced me to wait an extra hour until it was light out before I left. While waiting out the hour, I got a call from my boss saying all 3 of our lab facilities were closed for the day.