What Are Michael’s Crimes?

Now we know that Michael Cohen has been sentenced to 36 months in federal prison. What became very clear, however, is that a lot of that sentence was based on Cohen not becoming a cooperating witness in the Southern District of New York. Very specifically, Cohen pleaded guilty and seemingly cooperated over a number of crimes they’d caught him doing. But to become a cooperating witness (in the technical meaning and with the sentencing benefits) he needed to come in and tell his whole history, every crime he ever committed, every crime he knew information about. He was not willing to do that. Why?