How do I deal with this guy who is supposedly my friend?

Okay, this kid Logan who I go to school with is starting to annoy the **** out of me on Facebook. He acts all perverted and makes threats he won't go through with. He's a scrawny kid who talks like a girl and acts like one most of the time. Yesterday on a private chat he said "I will come on your face" and that "He would beat the sh*t out of me after school" and he always says at school that me and my girlfriend Meghan (I'm bi) "Are the cutest couple he's ever seen" But online he always says " b*tches" to me. He knows I could put him in a coma if I wanted to, and when I tell him to stop he keeps changing the subject on me. I have pictures of all the perverted things he's said so if he doesn't stop i'll tell the principle. But before I do that, is there anything I could do? Since we have known each other for years and he lives 4 houses down from me. I would really like some help.