I'm in love with my friend's girlfriend. What should i do?

My friend doesnt truly loves his girlfriend and considers it just as lust, but i have spent hours talking to his girlfriend and discovered that she is like my soul mate. It was me only who made them fall in love and now i become very rest-less when i see them together. i do my best to hide my feelings in front of them. They both consider me as their very good friend and so sometimes i feel bad or guilty when i think of wanting his girl friend. But i just cant help it. she is sooo like me. we have many many many things in common. she is the kind of girl that i always dreamed of and that i always wanted. so now the dilemma for me is that i cant be with her but dont wanna be without her. what the hell should i do now? so if anyone out there in this beautiful and wonderful world is able to understand me and my problem, then please help me. i would be really grateful to YOU...

ok the thing is that the more time they will spend together, the more chances are there of them falling in love. Although its lust from my friend's side as for now, he might fall in love with her someday very soon. Then what will i do?