Didnt Stop Him

We were having a family birthday party at our house for my mom. There was a lot of drinking going on and i had a bit too much so i decided to go lay down in my bedroom. A few minutes after laying down i heard my door open and some one came in. It was my brother in law, he came over to my bed and asked if i was alright. I told him yes just a little sleepy. I started to fall asleep when all of a sudden i feel him poking at my mouth with his cock. I knew this was wrong but i didnt stop him and just opened my mouth to except his cock. I had always been attracted to him so i started sucking his cock until he came in my mouth. he zipped up and said we shouldnt tell anyone about this. He left my room and I have never said anything to anyone .
I feel guilty about it but i did enjoy that he was into me and told him that i hope we can continue getting together. So since then we have fucked a few times . Love my sister but her husband is just to sxy to resist. I know im a bad sister. But must admit i am loving the sex between us. and ill never tell.rgfzqur