Irresistible Sister in Law

Viola and I were happily married and sexually satisfied for five years. We even used to talk in front of our best friends about how we were sexually still into each other.
Yes, we were bragging too much about the way she can pull me back to bed and make me aroused in a few minutes. And she kept bragging about my full manly and huge dick size.
Obviously, we love for alcohol and drinking most of the time, which made us that way. Not so shameless, but enjoying our sexual life.
Maybe it was only because of the alcohol. Not love as I had thought it to be.
Only one issue, I thought I have forgotten about it. It was a viola elder sister. She was yummy. And the day before my wedding to viola, I did it with her elder sister. Yes, I fucked that woman! And I loved it.
But I didn’t know that might happen after five years of re-uniting. I didn’t realize that viola’s sister wanted me that badly. 
'You can’t put the fire near gasoline, or it will burn everything around and even us!'