(2/2) I’ve had a HUGE crush on a trans male before, but I was under the impression he was cis. When I found out he wasn’t, it’s not that ALL the attraction went away, but my feelings did diminish slightly. Does that make me a horrible person? Serious question.

If you simply don’t have romantic or sexual feelings towards somebody because of something like their genitalia, skin colour, age or even something as small as their hairstyle, this isn’t your fault. You cannot control your sexual or romantic feelings, they’re innate.. This doesn’t make you a horrible person.
If you treat people with less respect and unequally because of those things then you’re being unfair, and depending on why, racist, sexist or ageist.
From the sounds of things though, you just seem not to have a sexual attraction towards people for certain reasons, and not that you just don’t like them.. If that makes sense? ^^
With love,