Ok the weirdest thing happened to me the other night and I'm still quite bewildered and don't know what to do so can any of you hep me maybe? I went out to a friend's party monday night and got drunk and got a taxi home and went upstairs to my room and I was so pissed that I just wanted to sleep so I stripped down naked and climbed into bed, well it's been so hot lately that I didn't put the sheets over me but my bedroom door was shut. (I live with my mom, step dad and sister). Anyway I woke up later on and my sister was in the room giving me oral sex! She was naked too and was completely sober, I pushed her off and asked her what she was doing while trying to cover myself and she lay down on the floor and begged me to f**k her, I told her to get out but she wouldn't leave she came up towards me and nearly sat on me but I got away and made her leave, since then she's apologised but said she is young and wants adventure and says I can go in her room any time I want. What should I do about this? I have no desire to have sex with my sister that's just wrong, any advice? Since then she has just carried on as normal.

P.S. I'm nearly 24 she's 19 and she's actually my step sister cos she's my step dad's daughter from another relationship and mom adopted her when she married my step dad.