Back Stabbers
There is a very powerful Midrash brought by Rashi in connection with the words, אכן נודע הדבר, now the matter is known.
The simple explanation is that Moshe now realized that it was known that he had killed the Egyptian, and he needed to run away from the law.
The Midrashic interpretation is that Moshe now understood what had been troubling him for a long time. How was it possible that one nation could be enslaved by another nation. Now that he saw that there were דיליטורין, back stabbers among the Jewish people, he realized why they deserved to be slaves.
The Prophet Isaiah warned us that מהרסיך ומחריביך ממך יצאו, that those who tear down and destroy will come from within. It is not the outside enemy that threatens us, but it is the traitors and disloyal from within that threatens our people.
Unfortunately, this realization of Moshe Rabbeinu rings true today. We need loyalty and unity among our people, in order to be strong. If we are, the outside enemies will never be able to harm us.