What can I do about my best friend?

I've been his friend for forever. I've been there for him when every girl hurt, cheated, and broke up with him. He got a new girlfriend that controls who he can and cannot talk to. She doesn't like me just because I'm a girl. I was his friend first so I think that he should be able to talk to me no matter what she says. She's so needy and tries to keep him from his girl friends. How can I tell him his girlfriend is a selfish ****** without threatening our friendship?