My friend who use to be a nerd

Ok so I have a friend who two years ago was the least popular person in the school.nobody was friends with him… Accept for me.now back then I wasnt the coolest either but I still was just a guy with some friends.so I decided to hang around with my nerdy friend and now in 2009.hes like the coolest person ever and im still as good friends with him still and all but its like I just faded away into the backround with the people I was ok friends a few years ago.but the reason why im asking this question is that theres a house party on in a few weeks but you have to be invited to go .he got invited but not me .I dont even want to go to be honest but thats not the point.the point is when I asked him whos party it is he said that he was told not to tell anyone…yeah I no right .he wont even tell his best friend who hes been hanging around with since we were 12(now im 16 and hes 17).after me single handedly made him meet new people over the past 2 years bringing him to every party there ever was and he wont even tell me whos party it is.thats pretty bad I think.I mean come on he barley knows these people.he wouldnt eben be in this position if it wasnt for me.if I was him id tell my best friend straight away just keep it on the down low.

What should I tell him? And what should I ask him for him to tell me whos party it is? And should I keep hanging around with him?hes my only real friend in school and id wouldnt really have a chioce but to hang around with him

Please give me good advice