Lesson Learned

Shannon felt as sense of vertigo looking down as Lisa head bobbed up and down on Jack's manhood. She reached her hand to a nearby wall to steady herself as she watched her former body pleasuring Jack in such an intimate way. In many ways it felt like an out of body experience, as if she was still in her original body, pleasing her man, and show how she was also looking at it. She steadied herself and noted Lisa's technique.
"She needs a little work". She thought to herself, "but she is more than making up for it with enthusiasm. And Jack sure doesn't seem to mind."
Jack was gasping slightly, and Lisa slowed down and looked up at him lustfully, not wanting him to finish to quickly. She slowed her pace, but continued, slowly fitting the entirety of his manhood into her mouth.
"She's not gagging." Sharon noted with surprise. "Maybe she has more skills than I thought?"
Suddenly it dawned on Sharon that she was just an observer. They were having a threesome, and somehow she had become the 'fifth wheel'. Well, she was going to take care of that.
Shannon started lifting her shirt up when she caught sight of Jack and Lisa's wedding picture hung up on the wall. The happy newly wed couple, Jack in a black tuxedo and tails, and Lisa in a classy flowing white that still managed to show off a hint of her cleavage. Shannon stared at the picture, of the gorgeous couple whose eyes gleamed with hope for the future. She thought of how during a drunken Halloween party, when she had still been Lisa, how she and the real Shannon, whose was dressed as a sexy nurse, had gone into the bathroom together and before she knew what was happening, Shannon was kissing her and out of excitement and drunkenness, she began to kiss her back. Remembering the moment, she thought it would have ended there and have been one of those crazy drunk friend stories to talk about from time to time, but then Jack had come in and before she could stop herself, she had pulled Jack into the mix. It had been wild and exciting, but the next morning the harsh reality of sobriety, she remember that Jack had fucked another woman right in front of her. She knew it was her fault and even thought was responsible for bring Jack into it, a part of her had hated him from that moment onward. When having another threesome came up again, she should have said no, but instead she tried to convince herself that seeing Jack with another woman wouldn't bother her a second time or a third, that hopefully she would become accustom to it and she could forgive him, but instead she soon found herself wanting to be with someone else. Jack would never have wanted a threesome with another guy, so soon she started hooking up with Joe. She knew it was just a way of getting 'even' with Jack, but it put even more pressure on their relationship. Soon they couldn't even be together if Sharon wasn't there, starting things up between Lisa and her husband, getting them both in the mood where she could stand to touch him again. And now that was all gone. They were starting from scratch again and maybe without Shannon around, they could be happy together.
Shannon quietly slid her shirt back down and silently slipped out of the room. She stopped, feeling her body need to rip off all of it's clothes and go right back in there.
"I can't do that to Lisa." She thought desperately. "Seeing Jack with Shannon now might not effect her the way it effected me, but I can't be the reason for my marriage failing twice.
She quickly scribbled a note on a piece of paper and started making her way towards the front door.