I don't think he is evil per se, but power corrupts, so when he got into power it slowly started to get to him. When the MC gets to WVM he has been in power for a couple of years and he wanted the biggest asset he could possibly have on the side of the school and most importantly, his side. Sadly for him, MC is so different from what he thought he would be (someone who could be bought with pussy, hence sending the cheerleaders after him) that all of his plans backfire to the point I was kinda waiting to see a Willie E. Coyote impression. He is only a puppet to himself.
About the spy, does it really have to be one of the girls? I mean, if it has to be one, then my bet is on Tia, she literally comes out of nowhere to get some dick, which granted, is a possibility, but when the woman tries to get some right in front of the mom?, that's a bit weird for me. Another possibility is Katie, even though in my opinion she is less malicious and more just trying to move forward in the world, she does seem to have her own plans, how much of those plans actually involve the MC in anything more than sex remains to be seen.
However, there is one person who might actually be involved, our beloved liver-failure eyed, Lee. My main reason is that he was "involved", for lack of a better word, with Damien, a known spy. Granted, he could just have been a secret lover for him and not know anything about what the other was doing, but maybe he was aware and collaborating? I dunno, just bouncing ideas.