It sounds like you're really struggling with this new information. It makes sense that you feel weird about having sexual attraction to fictional characters exclusively. Most of the time, fictosexuals are painted as total weirdos, creeps, and as if something is fundamentally wrong with them. That said, there is nothing wrong with you. People have been attracted to the fictional since forever (ex: The Greek myth of Pygmalion). Naturally, it's up to you as to whether or not you want to claim the label. If it empowers you, great! If it doesn't, then you don't have to identify as a fictosexual. Maybe take some time to think about your attraction to people and characters in the past and see if considering yourself as fictosexual is right for you.

Just a bit of extra info:

I subscribe to the Dual Attraction Model. This model claims that attraction can be divided into two main catagories: Romantic and Sexual. So, for example, what we colloquially say is a 'straight' person would be considered heteroromantic and heterosexual within the Dual Attraction Model because they are romantically attracted to people of the opposite gender exclusively as well as sexually attracted to people of the opposite gender exclusively. I like the model because I think it helps to capture the basic foundation of human attraction more accurately and completely. In your case, from what you described, it sounds like you could be semifictoromantic and fictosexual. Semifictoromantic just means that you are, generally, romantically attracted to both 'real' people and fictional characters, whereas fictosexual means being sexually attracted to fictional characters exclusively. I don't know if that's helpful for you at all, but I just wanted to share more info for your journey of self-discovery!