Thanks for sharing something so personal and hard with us.
It's absolutely not your fault. Unless I read this story wrong, you weren't the person who assaulted someone, this person assaulted you.
It is NEVER our fault when we are victims of assault. It is ALWAYS the sole responsibility of the person or people who chose to assault us. Always. After all, if they didn't make that choice, we wouldn't be assaulted. Yet, in pretty much every situation of assault, we could make a million different choices and would still probably have been assaulted simply because we had the unfortunate circumstance of being within reach of someone dangerous. You don't know he wouldn't have done this -- or harmed you in another way during -- had you had sex with him. But even if you had, having sex with someone we don't want to does us harm, too, so what's most likely is you would have been done harm no matter what because you were with someone intent on doing harm.
I'm so, so sorry this happened to you and that this person did this. I'm very glad you were able to get some justice with this, but, of course, that doesn't mean you don't have trauma.
Sexual orientation isn't about who we don't like or aren't into: it's about who we are. And the unfortunate truth is that women abuse and assault people too. Is it is frequent? Well, that depends on the kind of abuse we're talking about. By all means, patriarchy and the ways it's enabled some very toxic masculinity can make men more dangerous in some ways. But it's not just men, alas. Would that avoiding abuse, assault or other harm was that simple.
Either way, who you are attracted to probably has very little to do with this. But you know what? What if it is influenced by this -- or by how beautiful your third grade teacher was or by the fact that you like the western style of dress women wear more than what men do or because you like how Taylor Swift sounds better than how the Jonas Brothers do? Our sexualities are made of SO MANY major and minor influences (though the prevailing theory is that orientation is probably mostly formed when we're kids), there's no way we can link them to one thing only.
Also: being lesbian isn't something wrong with you or something broken. There's nothing that's more or less okay about any given orientation: they are all equally okay. They have to be, just like the diversity of our skin tones, our heights or weights, the color of our eyes or our diverse physical abilities have to be equally okay, because our orientations are just how we each are, outside our control or (for the most part) our choosing.
Your orientation isn't about this, I promise you. It was most likely formed long before this. But your orientation also isn't an injury or a failing. Loving and being into people is a positive force in the world, and that very much includes women who love and are into women. Take it in. <3
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. - Margaret Mead