During a awesome night of sex with my girlfriend, my step mom Kelly walked in on us. I'd literally just cum up my girlfriends asshole when she opened the door. So taking my cock out of my girlfriends ass, I was about to tell her to get out. Kelly had other ideas. She walked over to me, took a firm grip of my erect cock and lowered her head. My very good looking step mom licked my cock clean then sucked in my dick. My girlfriend didn't say a fucking word, not a peep.
After probably a minute of sucking on my dick, Kelly stopped, licked her lips and stood up. She smiled at me, looked at my girlfriend and said "I've longed to do that for some time". With that, my step mom of six years walked out.
This happened a fortnight ago and since then I've kind of kept out of Kelly's way. Not because I'm embarrassed or anything, but because I'm so afraid I'd want to fuck her. In fact I know now I definitely would.
My dad goes away soon with his golfing society for a week long break. I'll be all alone with Kelly, so if she gets her way from the comment she made two days ago, I'll want to be balls deep up my fathers wife. Kelly passed me going upstairs and pinching my as on the way past she said "Your dads away shortly, my asshole needs attention too honey".
Now what the fuck do I do......?