Making a baby with my Neighbor

I'm Mark 24 live at home with my parents both work and I'm a carpenter and usually off on weekends. Our neighbor Helen 36 married to Martin 42 was trying to start a family and it seemed there was something wrong. But unable to find any reason in their love making, she had a sample of his sperm tested and it wasn't a good report that came back. So she started to drink as Martian was away working at the time. I got home from working just before 6 and had the weekend off. Helen was smashed you could say and I went to have a soak in the hot tub on the back patio. My parents were away and wouldn't be back till late Sunday afternoon. Helen seen me soaking and came over to talk, she asked me how the water was and I said great. So she stripped off her clothes and joined naked in the hot tub. I got a hard-on and well I fucked her and after I took her inside and done her again. She went home Sunday lunch time and I had done a great job draining my balls into her. I never gave a thought to her getting pregnant and I don't think she thought about it either. I was hoping for a repeat every time I was home alone or she was nothing happened. Then I heard my mother telling my father Helen was pregnant and both Helen and Martin we delighted. It didn't strike as anything strange at the time, it was just Martin got Helen pregnant around the same time I was draining my balls into Helen. It wasn't until 10 days later and I was alone again that Helen came and saw me. She asked me not to tell anyone about sexual relationship, I agreed and she let me fuck her again, and every time after that we were alone. I'm not in love with Helen just like the sex and won't let it stop her and Martin being happy.