I can't stop Fucking my Sister

I'm Warren 33 and 6 years ago I visited my sister Grace then 24. I had recently finished university and had gotten a job in same city as Grace lived. Grace had married at 20 and her husband Clark was serving in the army. They had a son called Maxwell after Clark's father, then Clark was sent overseas and was killed just before he was to return home. That was 14 months before I visited Grace, Maxwell then 3 and Grace stayed in the same city as they had been before Clark deployment. Grace had been working near the local base at local Dentist's office as a receptionist. On my arrival I saw them both and with the help of my employer brought a 4 bed and 2 bath house. It was part of my employment contract, I get a house and they keep employees. I paid it off over the following years at almost no interest. Having a house and it being really too large for a single guy and not wanting to settle down straight away and also being closer to Grace's work then her own rental place. I asked her and Maxwell to move in with me, she decided to move in with me. I was fairly busy the first few months with work and dating several women. There wasn't any serious relationships at the time, but I got lucky a few times. When I took my first holidays from work Grace had also got some time off and I took her and Maxwell to a theme park for a weekend and then to the beach for the week following. We all enjoyed the holiday. But Grace and me got really close and after Maxwell was asleep and we had a few drinks I made a pass at Grace and we ended up in bed fucking. Next day I wasn't concerned about fucking Grace the night before at all and wanted to fuck her again. Grace was quiet all the morning and after lunch with Maxwell at a puppet show. I asked would she like to do it again, at first she said we shouldn't before we were brother and sister and it was incest. But I told her I had really enjoyed our sexual relations the night before and put my arms around her waist and pulled her close. Then kissing her and she agreed to go back to our room and have sex. I fucked her every chance I got and on our return home asked her to sleep with me every night. She agreed and a year later I got her pregnant and we had a baby girl Elizabeth. We're still living together and are free to date anyone we want too, Grace hasn't dated anyone else. I've dated several women, but still prefer Grace to them.