Most times you will not go to jail for self defense if you can prove to the police that you needed to fight off someone and protect yourself from that person.
I've had to hit someone before with my fist and knock them out before when they were trying to attack me so I had to hit them in the face myself but they hit me first.
I had witnesses around which really helped to let the cops know that I had to use self defense and you do have a right to defend yourself when someone is trying to harm you.
So if you have to use self defense then do so either way.
However in self defense you cannot kill someone if they're just trying to punch you but if they're about to shoot you or stab you then you can use deadly force.
You might get arrested for the self defense especially if the person died but most times you will not if you really had no other choice to use deadly force to defend yourself or your family.