I'm going to leave my friend after his epilepsy attack
Is you friend's epilepsy attack bothering you?
Yes, he has gone to a deep mental disorder
You should never leave you're friend in a bad situation like that. You should be concerned for your friend instead.
It's not that serious. I can just leave him and find a better friend.
That will make you the worse friend to have. You can always make new friends, while keeping the old one.