I met a girl in my college class who is a very nice girl. However, I think it's gonna be short lived. In a discussion in class she confesses she is bisexual. This will make me sound like the devil himself but I am not interested in dating or having sex with a bisexual woman. Did it once, got burned, don't trust them, so never again. We were supposed to go to a hockey game tonight but I told her I have other last minute plans that came up. In reality, I don't want to date her now. Am I a bad person for this preference?
No, you're not. I mean, I think your distrust is misplaced since obviously one person acting badly shouldn't define a group of people, but you're not a bad guy for not wanting to date someone because of previous bad experiences and hangups. That's a natural defensive reaction, even if it's not 100% rational. And we can decide to not date someone for literally any reason. No one has to date anyone, that's up to them and their own personal preferences.
No, nothing wrong with preferences. I'm not ashamed to admit I have never found Asians attractive. I'll have the utmost respect for anyone of any kind, but I've just never felt an attraction of that kind. And same with bisexuals, I've not wanted to date one either. As long as you're respectful about your preferences (e. g. you don't want to date a fat person, don't, but don't be mean to said fat person), then you deserve respect back!
You're not a bad person but I think it's a little short-sighted. What do you dislike about them? Bisexuals are people capable of enjoying sex and/or love both ways. Im slightly bisexual, I fell in love with a girl once and have kissed a few others. I like guys more often. It doesn't change the way I like guys and it doesn't change the way I handle relationships, when Im with someone Im all into that one person.
It doesn't make you a bad person. Everyone has their own preferences. Just let her know you only see her as a friend, so she doesn't keep wondering if she has a chance with you. Communication is key! Best of luck!