Using my Stepmother

I'm Alexander after my father and I live at home with him and his new wife Anne 35 my father's trophy wife. I'm a only child and lost my mother (heart attack) 12 years ago when I was 19. So after 4 years my father Alexander 62 remarried to Anne, she nice to me no evil stepmother crap. There's a prenup in place and any trouble she gets nothing, my father is a high price lawyer so it's water tight as they say. I had a car accident at 20 and have to use walking sticks with a brace on one leg. I usually work from home using my computer and have a bedroom on the ground floor. I do still drive and have a modified car for that purpose. Then in January my car was picked early and taken in for a service. So I was home and wasn't expecting my car till about 3pm, Anne hadn't seen my car picked up and so assumed I had gone to work. Anne as it turned out wasn't getting serviced by my father and decided to fuck a tradesman. Bad luck for her doing outside my bedroom window at the back of the house. I watched and filmed her going at it you could say. I waited until after the tradesman had left before making myself known to Anne. As I expected she was mortified that I knew and had filmed her as well. She said I might as well pack my bags she said. Why would you do that I asked, because when yo show father that he'll kick me out, so I might as well be ready she said. I didn't say I was going to tell him I said, why wouldn't you she asked. You being here he is calmer than when he has no one I said. So your not going to tell him she enquired, I'm not, but if your want a fuck again you might think of me. But its not a requirement of my silence I said. I left her to think it over, later on Alexander arrived home just my car turned up as well. Alexander had to go out of town quickly and and had come to pick up a bag he had gotten Anne to pack for him. He said he would drive the mechanic back as he was going there workshop on his way to airport. He was in the company car and it had a driver, so he left straight away with the mechanic. Anne asked me what I was doing that night and I said the usual nothing much. How about you and I do nothing much together then she asked. Sounds like a plan I said and she now regularly joins me in my bed ever since. She still fucks my father now and then but he isn't all that interested in sex these days. So I get plenty of sex from Anne, so when she missed her period it's good bet I'm the father of any child she might be carrying. She has only had sex with since the tradesman and couple of times with my father. My father doesn't take things at face value those and decided to be sure he had made the baby once it was confirmed Anne was pregnant. Being a cheap bastard as well, he was using the cheapest available DNA place available. It was lucky for Anne and me he was, he had told me he trusted Anne. But preferred to be cautious, as the DNA place was on the other side of town from his office. I offered to deliver his sample for testing so it could matched with baby later on. I took the precaution of getting tested myself, put his results in his safe for later checking. I had the combo and kept stuff there myself, on the birth of the baby girl a sample was obtained and tested and at 2 labs. Both labs had the same name on the possible father's test results, I got the results and it was confirmed as me being the father. So the results I gave my father said Alexander ? ? was the father the birth date had been changed on the envelope. Good thing we both have the same full name, I don't use junior as it makes me feel like a child. So my father little Katherine after my late mother is his. Anne still uses my services, but takes more care.