Wife's Older Sister

Little back story, my sister in law is an anoying bitch and I honestly can't stand her. On New Years my wife and I went to her sister's house to celebrate. Her husband drank way to much and was passed out by 11. My wife, who rarely drinks, was out by 1. Us three were on the couch, I was on one end, my wife in the middle passed out, and her sister on the other end. Her sister starts talking about how my wife brags about me and how pathetic her fat husband is in bed. I'll admit my sister in law is cute and fit for a woman her age (41), but I genuinely do not like her as a person. So I was just kind of nodding and letting her talk. I start to doze off and then she scoots over, reaches over my wife and starts rubbing on my chest, before long moves down to my dick. I looked at her but didn't say anything, but I did get hard. She got in the floor, moved over to me, and unzipped my pants. She pulled my dick out and started sucking. It felt pretty good, but I can confidently say my wife is more talented than her sister when it comes to sucking dick. After a few minutes she stood up, gently moved my wife over and straddled me. She pulled her shorts to the side and rode me slowly me for about 15 minutes until I came in her. She got off my lap and sucked my dick clean. I pulled my pants up and pulled my wife back to into my arms and my sister in law went to bed with her husband. Since then we have both acted like nothing happened. I honestly regret it, I mean it was decent pussy but I have a feeling, being the bitch she typically is, she might hold it over my head one day. On the otherhand she has been way more pleasant to be around since that night. Even my wife has mentioned how nice her sister has been lately.