Once I got through that obnoxious gate and then done with my emails, I pulled up some pics of my wife that I had taken way back then, some of them topless or nude, making even more mental comparisons to her then and her daughter now downstairs. I could hear them all laughing as they played their game, so I figured what the hell, and pulled out my Johnson for some relief while I recalled some of our fun times and these pics to remind me. I know I was enjoying myself immensely and could feel myself getting close when as I opened up my eyes a bit to again look at the latest picture on the screen, I noticed my step daughter standing at the top of the stairs watching my hand stroking. I about had a heart attack, but must not have hesitated, as she didn't look up at my face, but was watching intently. I quickly decided to see how this played out, after all, I was already caught so the damage was already done. I partially closed my eyes so I could watch her without her realizing it, and now with her attention my balls were boiling as I was stroking. I know I was as hard as I ever get, and they were full strokes up over the head and back down to the base, the tip all slippery from the fluids escaping even faster now. I could still hear the grandkids and my mother in law laughing downstairs, but she was watching as silent as she could, and now could even see her reaching down to rub herself, and for the first time looking up for a second to see if I was looking at her. I kept going and she quickly looked back down at the action. If I sped up a bit or slowed, her strokes would speed or slow to match my strokes.
I started shooting ropes, the first one almost reaching her some 10 or so feet away and I stood up stroking it and making the most of it, finally making it apparent I had opened my eyes and was staring back at her. I pretended shock as I was still stroking, and it took her several seconds to look up and notice me looking at her, probably about when I stopped stroking fully. the hand she was using to rub herself stopped then slowly came up to her mouth, and she suddenly said "oh, I came up to tell you we will be leaving shortly", and started to turn around. I don't know why, but I responded "sorry, I didn't know you had seen me, I apologize for that." she answered "its alright, it can happen to anyone" and she hurried down the stairs. this time as she opened the gate, it made all the noise it usually does when you try and open or close it. so now I started wondering how I might have missed that loud and annoying sound. I cleaned up, shut the computer down, and headed back downstairs. my mother in law was still playing the game with the grandkids, but almost done, Erin was getting their dog ready to go, and bagging things up from the kids. she made short eye contact with me, and then told the grandkids to "give grandpa a hug so we can go." they jumped up and hugged me, she stepped over for her usual hug but short armed it, making it even more awkward looking. She hugged my mother in law, and they headed out.
Now realizing that this will get back to my wife and she is about to start driving home, I decide to not try and defend this from behind, and I sent my wife a text to call me when she is headed home. My plan is to say what happened upfront so this can't get blown out of proportion. When she calls, I step outside the house and tell her I might have screwed up and filled her in, just the parts that I was caught, by whom and when she asked if I think her daughter actually saw something, I replied I didn't know, just that she seemed uncomfortable. I also had sent my step daughter a text "sorry again" to which she replied, "no big deal." My wife then called her daughter to try and calm the waters and get her take. Shortly after I got a call from my son in law, laughing and asking me how I got caught, and I told him I apparently didn't hear her fighting with that gate to come upstairs. He laughed again, and said she told him she felt guilty because she carefully climbed over the gate thinking I might be on the phone and didn't think to say anything as she came up the stairs. he said she made it sound like she had just come up the stairs and we saw each other right away, and while she knew what I was doing, didn't see anything. He was saying its all good, but I know from what I saw and how she acted, that wasn't the case at all.