Even though it was very distressing for you something good has come out of the situation as you will soon be helping other people who have epilepsy through volunteer work.
This will be very rewarding for you.
It is horrible seeing people have a fit, my Grandma has developed Epilepsy and the first time I saw her having a fit I cried. My grandma came round and wondered what all the fuss was about!
I have been told that when people have the fits they cannot feel anything and its much worse for people around then the actual person having the fit.