I don't know how I should handle this...

So to make a VERY long story short...I'm 25 and I'm a gay male. I have known my best friend for 10 years and I've had a crush on him since day one. Me and my other friend (straight girl) want to get together and I bring my best friend we hangout and then again the following weekend. We were all drinking we start watching a movie, they both get up and they fucked. We have been hanging out a couple of times since then and I always get super jealous, he and she both know I want him. How do I talk to my straight girlfriend and tell her how I feel?