I'm sorry, to be brutally honest about it, there is very little
you can do. Even if it can be proven that his friends had
intercourse witn you, it will be their words against yours whether
it was rape or consensual, unless the sun came up from the west and
you can get one of them to testify for you. And you will have a
hard time proving the former given that you willingly got yourself
so drunk, played the game, etc.
So where does that leave you? Knowing that you cannot do much about
what's past, the only way is forward. My motto in life - "If you
can't do anything about it, there's no point worrying about it."
Stop brooding about it - you have a choice whether you allow
something that has happened in the past affect your future. To be
frank, I won't be surprised if in that intoxcated state you were
actually aware of what was happening, especially since you
"enjoyed" it. So don't feel sorry for yourself. Just take this as a
major lesson learnt, and don't be so silly to get yourself into
this situation again. Seek official help, as suggested by others in
this forum, if you find that it is haunting you.
But remember - it is ultimately your choice whether or not it will
affect you for the rest of your life.