My bf best friend threatened me pls help?

My boyfriend of 2 years has this friend. There rlly close like best friends and I've used to be close to him too,plus his gf is one of my close friends. So anyway I was at a party w/ his gf and some of our friends and we all got rlly drunk so I ended up leaving the party without her so on my way home I ran into him and was rlly drunk and he got so mad at me that I left her there athat he started screaming at me calling me a f***ing wh*** and a spoiled b**** and that I'd be punished. Then he pushed me and started slapping my a** and groping me when i said stop. This was 2 nights ago and I'm rlly scared what do I do?!! Do I tell someone pls help.