Since "Hispanic" is a cultural designation, and not a racial one, I'd be willing to give Tex the benefit of the doubt if-if-if he was adopted as a very young child. Now, if he was adopted at, say, 17 or 18, then forget it.
You need to expose this school so we all can know. This school needs to be publicly shamed! If I were in your position, I would get the media involved. They practiacally tried to sabatoge you based on incomplete information.
I think most adopted children would say that they identify with their parent's race. Regardless. I happen to know a blonde haired blue-eyed little boy whose parents are both hispanic. He just ended up with some buried recessive genes. Does that mean he's not an URM? Being an URM is not edxclusively about your skin color. It's about overcoming years of oppression and poverty. I personally think their should be a box for poor white folks too.
Big Tex lied and got caught. He is a liar. He tried to be slippery and write his "addendum" to cover his butt, but when he checked "hispanic" his file made it to a separate pile from the white applicants. He got preferential treatment based on his lie, and as a person competing against Big Tex for a spot at Harvard, I'm outraged. He's as white as me, and his application should not have any weight over mine because of his lie.