I'm not gay. But I'm dreaming of it?

I have nothing against gay people. I support the gay community, I have two gay buddys. And people started a rumor around school that I had sex with my best friend (Who's straight too).
I have a boyfriend.
And I'm hopelessly in love with him.
But one of my friends is always irate at the fact that I'm straight, they think, I should be gay too.
They always pushed me to try and see girls.
None I never went with because I don't swing that way.
No big deal right?
Well you see I always have these night mares of being molested/raped. Normally it's by men, one time it wasn't. And scary enough it was one of my friends (Female with a questionable sex prefence, no one can tell if she's gay or straight cause she acts like she swings both ways, I suppose she's bi) who molested me. Weird thing is half way in I started liking it.
When I woke up I felt ashamed I can't even talk to said friend. Who now calls me non stop wanting to come over.
I know it's just a stupid dream. But I can't shake it.
I do and don't want to tell my boyfriend.
I feel like I've cheated =\.
But I'd never cheat on him. I have no desire to. And I wouldn't leave him for a girl. I'm not gay. So why did I have such a weird dream?