I am another who thought the OP handled the situation well. An assailant does not have to be visibly armed in order for one to be in fear of death or serious injury. The OP was assaulted and threatened and clearly had reason to prepare to defend himself, and stopped short of applying deadly force when he was able to extricate himself from his situation.
If I understand the first post correctly, though, you drove home with your assailant following you. I would not want him to know where I lived. Be careful if he makes bail or is otherwise freed.