Can you have your parents come over and help you move out? If you do it on your own, your boyfriend may get violent I am afraid as you said he prevents you from leaving the apartment. If your parents are there (or friends) then you will have more encouragement to leave and if things escalate, then you have support if you need to call the cops and such.

Edited to add...what he is doing amounts to imprisonment and as such is quite illegal. He cannot prevent you from leaving the apartment.