Having sex with my wife’s younger sister and her best friend

I posted here yesterday asking for opinions regarding swinging until some gentleman pointed me to correct subreddit.

As I mentioned in that post, the wife and I are open minded to some point, we agreed to have a "free day" where we have sex with whoever we want as long as we don't have to know who were they.

My choice was her sister and her best friend, I didn't see any problems with that until I heard some valid opinions about how I'm playing with fire, I guess they were right.

Anyway it all started last year, we decided to spice things up by having sex with other people on a specific day we agree on, I always had a thing for her 19 years old sister, it seemed that she was physically attracted to me -after yesterday's discussion with the people here I'm almost sure that she's just getting back at her sister since they don't have the best relationship- so I confronted her that I desire her and said she same, the wife and I agreed on a day, she left to "meet her friends" while I was almost sure that she's gonna have some wild sex with her ex boyfriend.

I called the sister and told her that I'm coming to her place, when I arrived there I saw a totally different woman, it seemed like she was prepared for this moment -or she's a slut- she was wearing the sexiest lingerie I have ever seen, I'm used to have sex with different women since high school, but this time I was blushing because wow! Her breasts are fairly big and round, she has an amazing body and amazing curves, I know that she did something to puff her lips but man they were puffy.

We talked a little bit and had some drinks, she smoked some cigarettes and told me that she's ready, she got naked and I was about to explode just from seeing her naked, I wanted to believe that everything was natural, but I only see these bodies in pornos, I also got naked and jumped on her like a predator, I almost ate her lips from the way we were kissing, it was passionate not just lusty, my junk was reaching out just to go inside her, she said do me from the ass because I know you won't last long in the first round, damn that hurts! I lubed her ass and knew for sure that she has frequent anal, I mean my thing got sucked in, I have anal with my wife so I know how hard it should be the first few times, but I can assure that this hole is used many times.

Anyway, she was right, I came within 2 minutes, and sucked me for a few minutes until I had another raging boner.

This time I was ready, I kept saying to myself "you have to screw her well or I ain't gonna a second chance" so while drilling her vagina I was thinking about video games, the war in the middle east, how my boss is gonna shout at me because I'm late in handing a report, we stayed like this for almost 20 minutes until I broke down and shot my load, she was amazed talking about the best sex ever and how she came 5 times…honestly I don't care if she was lying, this is an achievement to last around 20 minutes in a girl like that.

We had sex like 10 times since then and I'm having a hard time thinking about a way to stop doing it with her… In the end I consider it a physical relationship and I'm not willing to lose my wife for an hour of sex every now and then.

Source: reddit.com/r/gonewildstories/comments/3g4e4u/having_sex_with_my_wifes_younger_sister_and_her