This does not sound like an institutional action. Something similar happened during freshman year of college in one of my classes. The people who collaborated (and as a result cheated) ended up with a 0 on an assignment that was 3% of your total grade. It never went beyond the reaches of the classroom, thus was not an institutional action. It seems like things were kept within the classroom in your case. Consider yourself lucky. Don't put yourself in such a position again!