I admire you Anthony for finding a place like this to seek some advice. It's tough when you are put into a situation like that. I think Leed made a good point about whether a cheater is good friend material: I think you would be better off alone for a while than to have a friend like that.
Some years ago I took a class taught by a terrible professor: we could never get a clear answer from the man. The WHOLE class resorted to cheating. I dropped the class and never reported it. I live with it but will always regret never speaking to the dean about the problem.
When my sister was in college, a pair of students broke school rules: they were in love and living together in a dorm. It was common knowledge, but blatently flauted the conservative school's code of conduct. An acquaintance reported their living arrangements to the dean. The young couple were punished, but the young man who reported them was also punished: his fellow students went out of their way to ignore him, snub him, and otherwise ostracize him. He graduated but was friendless.
Your friend "Louis" has not done himself or his classmates any favors by cheating. He's misrepresenting himself while degrading the value of the work done by his classmates. You can make more friends who better reflect the person you are and want to be. It's a difficult decision, but if I had it to do over again, I would not hesitate to report the students who were cheating.