What might be behind this peculiar " fantasy"?

this is going to sound really straightforward but it could be that you wish to be a guy and wish to be "brutal" like the guys who brutilized her but you're not and you feel like the guy who was held down and trapped but you feel angry that other people are doing this/able to do this. my suggestion to you use rope or handcuffs or just date someone who's skinny and short.