This is a terrific article about dissociation:
To view a great video on the effects of trauma on your Autonomic Nervous System please view: https://www.youtube.com/watch?v=ZdIQRxwT1I0
Another great video on how trauma, the brain and behaviour, please view: https://www.youtube.com/watch?v=4fPAANjtMlI
Apps for general counselling use in between sessions or to teach you some general calming skills include:
headspace
Smiling Mind
Calm
This Way Up