Can I go to jail for killing in self defense?

An assault is a threat of bodily harm with an apparent ability to cause the harm. It is both a crime and a tort and, therefore, may result in either criminal or civil liability.

If someone puts their hands on you in a threatening manner you are allowed to use the force necessary to escape or to defend yourself from harm, but only the amount necessary and no more. This is self-defense.

The two are not mutually exclusive. What you believe to be self-defense and present evidence in support of, is not necessarily so to the courts.

In short, if you defend yourself, the courts may still rule against you and yes, you may go to jail.