How long should I let her sleep?

My baby had a really rough day yesterday. Her dad left me when I was 26 weeks pregnant, and we now have a custody schedule for our 3 month old baby.  The poor girl is subject to sitting in the car for 2 hours (there and back) every time he takes her and often times she cries non stop during his time with her. Yesterday was one of those days. When I got her back she stopped crying, but her eyes were still so red. I put her to bed at 9 PM and she has been asleep for 9.5 hours already. When (if ever) do I wake her up to feed her? Should I just let her recover from the trauma yesterday?