dfwmale

Hi,
I am certain this situation has been documented and discussed often. I have always been attracted to my wife's younger sister since we married 21 years ago. For the record I am 51, my wife is 45 and her sister is 38. I have spent time with her in the past when I travel on business to her home town. We usually go out to dinner, have some drinks, and have even done some sightseeing together. A couple of times we have spent the entire day together.
On her last visit here (she is here about 7 or 8 times a year to see her nephew and niece) she has been making some open moves. For example when I picked her up at the airport she gave me a long kiss and held my hand and touched me on the drive home. We were alone a few times when everybody else was out of the house and she sat next to me on the couch and we started flirting and teasing each other. This led to about an hour of kissing, touching and hugging but it has not progressed beyond that yet. She has said that she finds me attractive and has for years, I feel the same but at this point it seems crazy to go any further with her. She has never married and has had only one serious boyfriend that she threw out.
I appreciate hearing from married guys who might have been or are in similar circumstances.