Cheating girlfriend

One night after going to the club with my girlfriend and my best friend we get back to our place my friend sleeps on the couch and me and my girlfriend and I go up to bedroom we have sex and go to bed I wake up about 2 hours later and I hear a moaning sound coming from downstairs I slowly walk down stairs I get to the bottom and look over at the couch my best friend is lacking my girlfriends pussy I slowly sit at the bottom of the stairs and watch as he is making her cum everywhere then before I know it he pulls his cock out and my girlfriend starts sucking him off I'm getting pretty hard by now if you can only imagine I'm getting worked up thinking about him fucking her then he bends her over and slowly slides his cock in to her soaked pussy I watch them fuck for about 45 mins then he puts her on her knees and cums all over her face it was the biggest turn on for me to watch her fuck another guy!!