A threat in itself is not necessarily a terrorist threat.  However, the law is very broad these days and pretty much any kind of threat is now called a terrorist threat since the penalties are stronger.  The actual legal term at play here is called assualt.  An assualt doesn't have to take place with somebody actually hurting you.  An assualt takes place if you feel you are in immediate and imminent danger of bodily harm.  the assualter must have made an overt act such as raising their fist or brandishing a knife for it to move froma  simple threat (not illegal) to assualt. If this was not the case and you escalated the situation to violence then you are indeed guilty because you did the wrong thing.  If on the other hand you had reason to believe he was about to attack then that would be a justification for self defense.

Check out the link below for more details and definitely get yourself a lawyer.  This is serious stuff that could follow you the rest of your life.