There is a lot of checks and ballances in the criminal justice system, and plenty of room for discretion on the part of officers, prosecutors, judges, and juries. What it boils down to is if you acted in a REASONABLE manner given the situation.
What is deemed reasonable largely depends on people in your area. Police in your area may or may not have a positive attitude towards civilian gun overship. The same goes for District or County Attorneys, Sheriffs, and Judges, except they're elected officials, and they will likely side with the popular opinion of the people around you. Politics should not be underestimated in this regard.
However, if you broke any laws, or think justification of your actions is lacking it would be a good idea to lawyer up as soon as possible. Depending on your political climate the police may be out to confiscate as many guns as possible.
Finally, expect the police to take the gun you used to defend yourself as evidence. As long as you are found not guilty it should be returned to you. Keep in mind the police's evidence lockers may not preserve your firearm as well as your gun safe that has humidity control.
Slow is Smooth. Smooth is Fast.