I just want to emphasize the point that these sorts of fantasies are really, really common. I have them too (and I'm female) so please don't feel like you are alone or "weird". that's how I felt most of my life until my T informed me of this. It was so liberating!

I agree with the others. Let yourself enjoy the fantasies if that's what gets you off. Why repress it? And if you want to actually act them out that's okay too. Just be sure you go slow and be sure you find the right person to do it for you. You don't want to find someone who really is an asshole, just someone who can convincingly ACT like one.

For me, it can be really cathartic to do this. I have no idea why my brain works like this but ultimately it doesn't matter. I just like it and I'm lucky enough to have someone I feel safe and comfortable enough with to act it out. I have a relationship with a guy (sort of a friends with benefits guy) who I know is a really really good person and a great friend to me when I need it, but the nature of our relationship is such that we play a kind of D/s game where he treats me really meanly. If you didn't know any better, you'd think he was a complete jerk but it gets me off, it gets him off and afterwards we come back to reality and he hugs me and I know he's a good guy again.

Here are the most important points:
1.) You're not the only one who likes that stuff and
2.) As long as it doesn't hurt anyone else, do what you like. Sex should be fun!

Enjoy!