So many hugs (without encroaching on your comfort level) to you.
It is NOT your fault that you ended up in this relationship. It is NOT your fault that this guy is like your father. Our brains do things behind our backs sometimes that are so beyond our control. I mean, I guess that's a bit obvious. If it were up to me, I wouldn't choose to have a single flashback. Ever.
With that said, is there anything you can do to make yourself feel safe? Meditation? More virtual hugs?