Yes, don't feel bad because of your fantasies. Some people are into abuse, humiliation or even S&M, even though in their real, day-to-day life, they'd never accept such treatment. I don't know why some of us have what I'll call non-vanilla or kinky fantasies, but it doesn't mean you'd want it in real life. You might enjoy acting out the fantasy, but it's not the same as someone harming you. In fantasy, especially when it's in your head, you are in control, you control what happens, how hard, how fast, how often.

If it bothers you too much, though, I would suggest seeing a sexual therapist who might be able to explain it better, and help you deal with it. But don't think you're a bad person because of it.