This girl that I always wanted to be with said she’s horny and really wants sex but now she doesn’t even talk to me. Why?

Because she’s horny and really wants sex with someone who is or others who are not you and regrets telling a person she doesn’t desire (that fancies her nonetheless) that very personal information.

She’s guessing your one-sided interest is probably going to turn into seething resentment and a possible ugly confrontation from you if she tells you that straight out so she’s probably hoping you’ll take the hint and shove off without making a scene.

Do yourself and her a favor and take that hint. In the future, reserve your erotic interest for someone who unambiguously shows you she wants you as much as you want her.

All the best.