I'm so sorry that beliefs such as your bf's father has still exist.
May I ask why you tolerate his parents visiting? I think I would have to put my foot down with my bf and tell him 'no more.'
It sounds to me like the father's snooping in your bathroom and personal items is because he is intrigued by you.
As far as your bf's behavior resembling his father's, I would find it unacceptable as well and would tell him so and if he didn't change his ways I would be ought of there.
I'm so sorry you have to face this. I hope you have the courage to stick up for your dignity.