Completely disgusted with a friend?

I have 2 best buds, N and F. Lately, we always spent our times together, like going to the library, watching movies and stuffs. But I realised that one of them, I call him N, was acting kinda weird. He was like, gay. I mean, he really loves the other one! I can see he would act differently when F is with him. He started to become queer(catwalks, playing with hair and stuffs). He likes to act cute when F is with him, ewww! He even thought that I was jealous of him, getting closer with F. And, one day, I was reading at the library, and N came to me, acting strangely and it was so disgusting. He was like a female prostitute or something, making a sound like "mmm" when he was telling me story of him and F. I was really disgusted with this guy, I mean, I would scream if I could. I asked him "Hey man, don't you think you have changed, a lot? and I think you're not really you anymore" and he got very angry and yelled at me.What should I do? This guy can drive me mad. I really don't like him anymore. I tried to leave him, but he keeps coming for me. =(