What if I show you?

My girlfriend and I have been together for just over a year now and she is an incredible person. She tells me one evening over a glass of wine that she had a few flings in the past with girls and she really enjoyed it but was I okay knowing that? It was one of the hottest things that I had thought about so I asked her to tell me more about it which she did in great detail. It turned out that the last one was only a year before she met me and it was with one of her married work friends who had never been with another woman. The more she told me, the more aroused we both got. She deliberately slowed the pace of the story and got me to do to her, everything that she had done to her friend while she experienced it from the perspective of the other girl. It was like I was there as she told every intricate little detail of what her fingers were doing to her clothes then skin and how she positioned her on the sofa and kissed her gently to calm her down. How she slowly removed her jeans and played over her panties to see if she would go further. I did everything that she told me, to the letter; and she had so many climaxes with my fingers and tongue, she even had a climax while I was sucking and playing with her nipples. She asked me to put my fingers in her mouth to stop her from making too much noise which I did and she had a huge shaking climax. Obviously, she couldn't continue the story then but we made love and it was quick but amazing. After sex, she told me that she really did have to put her fingers in her friend's mouth as she was getting so loud that she worried it would wake her husband up who was sleeping upstairs. And that the taste of her wet fingers made her friend come so much that she could taste it for days. It was that memory that caused her to have the huge orgasm at the end. "I think I could do It!" she says "Do what?" I ask. "Do that with another girl and let you watch. Only as long as you don't say anything or try to join in which would ruin it for me. If you can do that we will have great sex after!" And at that she cuddles up to me and falls asleep.