I agree, but to an extent. In practice, whistle blowing is necessary to prevent actual harm. There is little, if any, actual harm possible in this situation.
The question comes to be "where do the balls lie?"
In a case of "cheating" in its actual sense, it would be ballsy to turn someone in, especially "a friend"
in this instance, (until we found out later, thanks OP) it wasn't clear cut, and it sounded like the OP just had his/her panties in a twist because he/she might be getting gypsied out of a higher grade.
Turns out this wasn't the case, the OP's "friend" is a ******ed cheat, the professor is stupid, everyone in this thread is stupid, and I, especially, am stupid for actually participating instead of just making a joke like usual.
allow me to rectify this:
you're not going to hell if you make the wrong decision here, you're going to hell because you touch yourself at night.
there, now we're all better.