Cheating girlfriend

I have just had beautiful sex with my girlfriend I went into the shower clean myself up and make my pussy fresh again for her when I came back I could hear noises in my brothers room I opened the door slowly saw my girlfriend riding my brothers cock I was angry I was going to go over and have it out with them But my nipples got hard and my pussy started to get damp watching her impaled on my brother as if my hands most of my own went between my legs and fingered myself just as he shot in her she got off turned around and said to me you told me I could have him we kissed and smiled at one another