I'm going to brutally honest. That was selfish and disgusting. I literally threw up in my mouth reading this. Do you have serious self esteem issues? Normal people don't do that to a married man, even worse to their brother-in-law. But you did one thing right. You felt guilty. So that proves that your heart isn't totally cold and hard and black. Good for you. Enough bashing, you need to solve this problem. First, talk to your brother-in-law. Apologize. Tell him that it means nothing, and you were being selfish, and feel like a slut. Then apologize to your sister. If she finds out by anybody other than you, she will be a livid, pissy mess. And will have all the right too. Now that I think about it, she's still going to be a livid, pissy mess, more along the lines of a *****. Good luck. I hope you realize that your selfish impulses most likely ruined ur sisters marriage, and damaged your relationship with her forever. Seriously, how stupid can you be? I'm only 15, but i feel as if I am reprimanding a dumb child. Here, take a gold, firkin' star. You deserve it, worst sister of the year. Hope this helps. You disgust me.