If you were my daughter and someone got in your face in a threatening manner, I would be contacting the authorities and a lawyer to advise this person that he is no longer welcome and it sounds as if a restraining order may be necessary.
Never under any circumstances let someone threaten you and do nothing. The next time may not be a threat - it may be real. I don't want to scare you - and I am going out on a limb - but this is not acceptable behavior on any level.
If you have been threatened, the first call you may wish to make would be to the police.
If hiring an attorney is not financially possible, you might ask around for free legal aid services in your area.
Call the police and have him removed from the apartment if he is not on the lease. You also might want to check your lease--if you have been charging him rent and your lease says "no subletting" you could be in trouble, as well.